1436 lines
50 KiB
Python
1436 lines
50 KiB
Python
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# Scanner produces tokens of the following types:
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# STREAM-START
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# STREAM-END
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# DIRECTIVE(name, value)
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# DOCUMENT-START
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# DOCUMENT-END
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# BLOCK-SEQUENCE-START
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# BLOCK-MAPPING-START
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# BLOCK-END
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# FLOW-SEQUENCE-START
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# FLOW-MAPPING-START
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# FLOW-SEQUENCE-END
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# FLOW-MAPPING-END
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# BLOCK-ENTRY
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# FLOW-ENTRY
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# KEY
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# VALUE
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# ALIAS(value)
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# ANCHOR(value)
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# TAG(value)
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# SCALAR(value, plain, style)
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#
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# Read comments in the Scanner code for more details.
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#
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__all__ = ['Scanner', 'ScannerError']
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from .error import MarkedYAMLError
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from .tokens import *
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class ScannerError(MarkedYAMLError):
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pass
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class SimpleKey:
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# See below simple keys treatment.
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def __init__(self, token_number, required, index, line, column, mark):
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self.token_number = token_number
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self.required = required
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self.index = index
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self.line = line
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self.column = column
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self.mark = mark
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class Scanner:
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def __init__(self):
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"""Initialize the scanner."""
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# It is assumed that Scanner and Reader will have a common descendant.
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# Reader do the dirty work of checking for BOM and converting the
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# input data to Unicode. It also adds NUL to the end.
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#
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# Reader supports the following methods
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# self.peek(i=0) # peek the next i-th character
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# self.prefix(l=1) # peek the next l characters
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# self.forward(l=1) # read the next l characters and move the pointer.
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# Had we reached the end of the stream?
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self.done = False
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# The number of unclosed '{' and '['. `flow_level == 0` means block
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# context.
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self.flow_level = 0
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# List of processed tokens that are not yet emitted.
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self.tokens = []
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# Add the STREAM-START token.
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self.fetch_stream_start()
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# Number of tokens that were emitted through the `get_token` method.
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self.tokens_taken = 0
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# The current indentation level.
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self.indent = -1
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# Past indentation levels.
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self.indents = []
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# Variables related to simple keys treatment.
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# A simple key is a key that is not denoted by the '?' indicator.
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# Example of simple keys:
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# ---
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# block simple key: value
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# ? not a simple key:
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# : { flow simple key: value }
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# We emit the KEY token before all keys, so when we find a potential
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# simple key, we try to locate the corresponding ':' indicator.
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# Simple keys should be limited to a single line and 1024 characters.
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# Can a simple key start at the current position? A simple key may
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# start:
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# - at the beginning of the line, not counting indentation spaces
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# (in block context),
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# - after '{', '[', ',' (in the flow context),
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# - after '?', ':', '-' (in the block context).
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# In the block context, this flag also signifies if a block collection
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# may start at the current position.
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self.allow_simple_key = True
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# Keep track of possible simple keys. This is a dictionary. The key
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# is `flow_level`; there can be no more that one possible simple key
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# for each level. The value is a SimpleKey record:
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# (token_number, required, index, line, column, mark)
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# A simple key may start with ALIAS, ANCHOR, TAG, SCALAR(flow),
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# '[', or '{' tokens.
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self.possible_simple_keys = {}
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# Public methods.
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def check_token(self, *choices):
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# Check if the next token is one of the given types.
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while self.need_more_tokens():
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self.fetch_more_tokens()
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if self.tokens:
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if not choices:
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return True
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for choice in choices:
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if isinstance(self.tokens[0], choice):
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return True
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return False
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def peek_token(self):
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# Return the next token, but do not delete if from the queue.
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# Return None if no more tokens.
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while self.need_more_tokens():
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self.fetch_more_tokens()
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if self.tokens:
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return self.tokens[0]
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else:
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return None
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def get_token(self):
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# Return the next token.
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while self.need_more_tokens():
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self.fetch_more_tokens()
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if self.tokens:
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self.tokens_taken += 1
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return self.tokens.pop(0)
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# Private methods.
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def need_more_tokens(self):
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if self.done:
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return False
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if not self.tokens:
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return True
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# The current token may be a potential simple key, so we
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# need to look further.
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self.stale_possible_simple_keys()
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if self.next_possible_simple_key() == self.tokens_taken:
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return True
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def fetch_more_tokens(self):
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# Eat whitespaces and comments until we reach the next token.
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self.scan_to_next_token()
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# Remove obsolete possible simple keys.
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self.stale_possible_simple_keys()
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# Compare the current indentation and column. It may add some tokens
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# and decrease the current indentation level.
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self.unwind_indent(self.column)
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# Peek the next character.
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ch = self.peek()
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# Is it the end of stream?
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if ch == '\0':
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return self.fetch_stream_end()
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# Is it a directive?
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if ch == '%' and self.check_directive():
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return self.fetch_directive()
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# Is it the document start?
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if ch == '-' and self.check_document_start():
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return self.fetch_document_start()
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# Is it the document end?
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if ch == '.' and self.check_document_end():
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return self.fetch_document_end()
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# TODO: support for BOM within a stream.
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#if ch == '\uFEFF':
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# return self.fetch_bom() <-- issue BOMToken
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# Note: the order of the following checks is NOT significant.
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# Is it the flow sequence start indicator?
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if ch == '[':
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return self.fetch_flow_sequence_start()
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# Is it the flow mapping start indicator?
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if ch == '{':
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return self.fetch_flow_mapping_start()
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# Is it the flow sequence end indicator?
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if ch == ']':
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return self.fetch_flow_sequence_end()
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# Is it the flow mapping end indicator?
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if ch == '}':
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return self.fetch_flow_mapping_end()
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# Is it the flow entry indicator?
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if ch == ',':
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return self.fetch_flow_entry()
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# Is it the block entry indicator?
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if ch == '-' and self.check_block_entry():
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return self.fetch_block_entry()
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# Is it the key indicator?
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if ch == '?' and self.check_key():
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return self.fetch_key()
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# Is it the value indicator?
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if ch == ':' and self.check_value():
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return self.fetch_value()
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# Is it an alias?
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if ch == '*':
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return self.fetch_alias()
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# Is it an anchor?
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if ch == '&':
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return self.fetch_anchor()
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# Is it a tag?
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if ch == '!':
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return self.fetch_tag()
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# Is it a literal scalar?
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if ch == '|' and not self.flow_level:
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return self.fetch_literal()
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# Is it a folded scalar?
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if ch == '>' and not self.flow_level:
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return self.fetch_folded()
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# Is it a single quoted scalar?
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if ch == '\'':
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return self.fetch_single()
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# Is it a double quoted scalar?
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if ch == '\"':
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return self.fetch_double()
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# It must be a plain scalar then.
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if self.check_plain():
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return self.fetch_plain()
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# No? It's an error. Let's produce a nice error message.
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raise ScannerError("while scanning for the next token", None,
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"found character %r that cannot start any token" % ch,
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self.get_mark())
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# Simple keys treatment.
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def next_possible_simple_key(self):
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# Return the number of the nearest possible simple key. Actually we
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# don't need to loop through the whole dictionary. We may replace it
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# with the following code:
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# if not self.possible_simple_keys:
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# return None
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# return self.possible_simple_keys[
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# min(self.possible_simple_keys.keys())].token_number
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min_token_number = None
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for level in self.possible_simple_keys:
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key = self.possible_simple_keys[level]
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if min_token_number is None or key.token_number < min_token_number:
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min_token_number = key.token_number
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return min_token_number
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def stale_possible_simple_keys(self):
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# Remove entries that are no longer possible simple keys. According to
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# the YAML specification, simple keys
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# - should be limited to a single line,
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# - should be no longer than 1024 characters.
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# Disabling this procedure will allow simple keys of any length and
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# height (may cause problems if indentation is broken though).
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for level in list(self.possible_simple_keys):
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key = self.possible_simple_keys[level]
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if key.line != self.line \
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or self.index-key.index > 1024:
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if key.required:
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raise ScannerError("while scanning a simple key", key.mark,
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"could not find expected ':'", self.get_mark())
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del self.possible_simple_keys[level]
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def save_possible_simple_key(self):
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# The next token may start a simple key. We check if it's possible
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# and save its position. This function is called for
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# ALIAS, ANCHOR, TAG, SCALAR(flow), '[', and '{'.
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# Check if a simple key is required at the current position.
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required = not self.flow_level and self.indent == self.column
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# The next token might be a simple key. Let's save it's number and
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# position.
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if self.allow_simple_key:
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self.remove_possible_simple_key()
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token_number = self.tokens_taken+len(self.tokens)
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key = SimpleKey(token_number, required,
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self.index, self.line, self.column, self.get_mark())
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self.possible_simple_keys[self.flow_level] = key
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def remove_possible_simple_key(self):
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# Remove the saved possible key position at the current flow level.
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if self.flow_level in self.possible_simple_keys:
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key = self.possible_simple_keys[self.flow_level]
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if key.required:
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raise ScannerError("while scanning a simple key", key.mark,
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"could not find expected ':'", self.get_mark())
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del self.possible_simple_keys[self.flow_level]
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# Indentation functions.
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def unwind_indent(self, column):
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## In flow context, tokens should respect indentation.
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## Actually the condition should be `self.indent >= column` according to
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## the spec. But this condition will prohibit intuitively correct
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## constructions such as
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## key : {
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## }
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#if self.flow_level and self.indent > column:
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# raise ScannerError(None, None,
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# "invalid indentation or unclosed '[' or '{'",
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# self.get_mark())
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# In the flow context, indentation is ignored. We make the scanner less
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# restrictive then specification requires.
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if self.flow_level:
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return
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# In block context, we may need to issue the BLOCK-END tokens.
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while self.indent > column:
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mark = self.get_mark()
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self.indent = self.indents.pop()
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self.tokens.append(BlockEndToken(mark, mark))
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def add_indent(self, column):
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# Check if we need to increase indentation.
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if self.indent < column:
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self.indents.append(self.indent)
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self.indent = column
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return True
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return False
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# Fetchers.
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def fetch_stream_start(self):
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# We always add STREAM-START as the first token and STREAM-END as the
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# last token.
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# Read the token.
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mark = self.get_mark()
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# Add STREAM-START.
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self.tokens.append(StreamStartToken(mark, mark,
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encoding=self.encoding))
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def fetch_stream_end(self):
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# Set the current indentation to -1.
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self.unwind_indent(-1)
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# Reset simple keys.
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self.remove_possible_simple_key()
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self.allow_simple_key = False
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self.possible_simple_keys = {}
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# Read the token.
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mark = self.get_mark()
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# Add STREAM-END.
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self.tokens.append(StreamEndToken(mark, mark))
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# The steam is finished.
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self.done = True
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def fetch_directive(self):
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# Set the current indentation to -1.
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self.unwind_indent(-1)
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# Reset simple keys.
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self.remove_possible_simple_key()
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self.allow_simple_key = False
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# Scan and add DIRECTIVE.
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self.tokens.append(self.scan_directive())
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def fetch_document_start(self):
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self.fetch_document_indicator(DocumentStartToken)
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def fetch_document_end(self):
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self.fetch_document_indicator(DocumentEndToken)
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def fetch_document_indicator(self, TokenClass):
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# Set the current indentation to -1.
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self.unwind_indent(-1)
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# Reset simple keys. Note that there could not be a block collection
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# after '---'.
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self.remove_possible_simple_key()
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self.allow_simple_key = False
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# Add DOCUMENT-START or DOCUMENT-END.
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start_mark = self.get_mark()
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self.forward(3)
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end_mark = self.get_mark()
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self.tokens.append(TokenClass(start_mark, end_mark))
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def fetch_flow_sequence_start(self):
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self.fetch_flow_collection_start(FlowSequenceStartToken)
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def fetch_flow_mapping_start(self):
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self.fetch_flow_collection_start(FlowMappingStartToken)
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def fetch_flow_collection_start(self, TokenClass):
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# '[' and '{' may start a simple key.
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self.save_possible_simple_key()
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# Increase the flow level.
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self.flow_level += 1
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# Simple keys are allowed after '[' and '{'.
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self.allow_simple_key = True
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# Add FLOW-SEQUENCE-START or FLOW-MAPPING-START.
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start_mark = self.get_mark()
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self.forward()
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end_mark = self.get_mark()
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self.tokens.append(TokenClass(start_mark, end_mark))
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def fetch_flow_sequence_end(self):
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self.fetch_flow_collection_end(FlowSequenceEndToken)
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def fetch_flow_mapping_end(self):
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self.fetch_flow_collection_end(FlowMappingEndToken)
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def fetch_flow_collection_end(self, TokenClass):
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# Reset possible simple key on the current level.
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self.remove_possible_simple_key()
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# Decrease the flow level.
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self.flow_level -= 1
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# No simple keys after ']' or '}'.
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self.allow_simple_key = False
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# Add FLOW-SEQUENCE-END or FLOW-MAPPING-END.
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start_mark = self.get_mark()
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self.forward()
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end_mark = self.get_mark()
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self.tokens.append(TokenClass(start_mark, end_mark))
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def fetch_flow_entry(self):
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# Simple keys are allowed after ','.
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self.allow_simple_key = True
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# Reset possible simple key on the current level.
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self.remove_possible_simple_key()
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|
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# Add FLOW-ENTRY.
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start_mark = self.get_mark()
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self.forward()
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end_mark = self.get_mark()
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self.tokens.append(FlowEntryToken(start_mark, end_mark))
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|
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def fetch_block_entry(self):
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|
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# Block context needs additional checks.
|
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if not self.flow_level:
|
|
|
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# Are we allowed to start a new entry?
|
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if not self.allow_simple_key:
|
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raise ScannerError(None, None,
|
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"sequence entries are not allowed here",
|
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self.get_mark())
|
|
|
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# We may need to add BLOCK-SEQUENCE-START.
|
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if self.add_indent(self.column):
|
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mark = self.get_mark()
|
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self.tokens.append(BlockSequenceStartToken(mark, mark))
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|
|
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# It's an error for the block entry to occur in the flow context,
|
|
# but we let the parser detect this.
|
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else:
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pass
|
|
|
|
# Simple keys are allowed after '-'.
|
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self.allow_simple_key = True
|
|
|
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# Reset possible simple key on the current level.
|
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self.remove_possible_simple_key()
|
|
|
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# Add BLOCK-ENTRY.
|
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start_mark = self.get_mark()
|
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self.forward()
|
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end_mark = self.get_mark()
|
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self.tokens.append(BlockEntryToken(start_mark, end_mark))
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|
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def fetch_key(self):
|
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|
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# Block context needs additional checks.
|
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if not self.flow_level:
|
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|
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# Are we allowed to start a key (not necessary a simple)?
|
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if not self.allow_simple_key:
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raise ScannerError(None, None,
|
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"mapping keys are not allowed here",
|
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self.get_mark())
|
|
|
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# We may need to add BLOCK-MAPPING-START.
|
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if self.add_indent(self.column):
|
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mark = self.get_mark()
|
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self.tokens.append(BlockMappingStartToken(mark, mark))
|
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|
|
# Simple keys are allowed after '?' in the block context.
|
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self.allow_simple_key = not self.flow_level
|
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|
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# Reset possible simple key on the current level.
|
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self.remove_possible_simple_key()
|
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|
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# Add KEY.
|
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start_mark = self.get_mark()
|
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self.forward()
|
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end_mark = self.get_mark()
|
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self.tokens.append(KeyToken(start_mark, end_mark))
|
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|
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def fetch_value(self):
|
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|
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# Do we determine a simple key?
|
|
if self.flow_level in self.possible_simple_keys:
|
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|
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# Add KEY.
|
|
key = self.possible_simple_keys[self.flow_level]
|
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del self.possible_simple_keys[self.flow_level]
|
|
self.tokens.insert(key.token_number-self.tokens_taken,
|
|
KeyToken(key.mark, key.mark))
|
|
|
|
# If this key starts a new block mapping, we need to add
|
|
# BLOCK-MAPPING-START.
|
|
if not self.flow_level:
|
|
if self.add_indent(key.column):
|
|
self.tokens.insert(key.token_number-self.tokens_taken,
|
|
BlockMappingStartToken(key.mark, key.mark))
|
|
|
|
# There cannot be two simple keys one after another.
|
|
self.allow_simple_key = False
|
|
|
|
# It must be a part of a complex key.
|
|
else:
|
|
|
|
# Block context needs additional checks.
|
|
# (Do we really need them? They will be caught by the parser
|
|
# anyway.)
|
|
if not self.flow_level:
|
|
|
|
# We are allowed to start a complex value if and only if
|
|
# we can start a simple key.
|
|
if not self.allow_simple_key:
|
|
raise ScannerError(None, None,
|
|
"mapping values are not allowed here",
|
|
self.get_mark())
|
|
|
|
# If this value starts a new block mapping, we need to add
|
|
# BLOCK-MAPPING-START. It will be detected as an error later by
|
|
# the parser.
|
|
if not self.flow_level:
|
|
if self.add_indent(self.column):
|
|
mark = self.get_mark()
|
|
self.tokens.append(BlockMappingStartToken(mark, mark))
|
|
|
|
# Simple keys are allowed after ':' in the block context.
|
|
self.allow_simple_key = not self.flow_level
|
|
|
|
# Reset possible simple key on the current level.
|
|
self.remove_possible_simple_key()
|
|
|
|
# Add VALUE.
|
|
start_mark = self.get_mark()
|
|
self.forward()
|
|
end_mark = self.get_mark()
|
|
self.tokens.append(ValueToken(start_mark, end_mark))
|
|
|
|
def fetch_alias(self):
|
|
|
|
# ALIAS could be a simple key.
|
|
self.save_possible_simple_key()
|
|
|
|
# No simple keys after ALIAS.
|
|
self.allow_simple_key = False
|
|
|
|
# Scan and add ALIAS.
|
|
self.tokens.append(self.scan_anchor(AliasToken))
|
|
|
|
def fetch_anchor(self):
|
|
|
|
# ANCHOR could start a simple key.
|
|
self.save_possible_simple_key()
|
|
|
|
# No simple keys after ANCHOR.
|
|
self.allow_simple_key = False
|
|
|
|
# Scan and add ANCHOR.
|
|
self.tokens.append(self.scan_anchor(AnchorToken))
|
|
|
|
def fetch_tag(self):
|
|
|
|
# TAG could start a simple key.
|
|
self.save_possible_simple_key()
|
|
|
|
# No simple keys after TAG.
|
|
self.allow_simple_key = False
|
|
|
|
# Scan and add TAG.
|
|
self.tokens.append(self.scan_tag())
|
|
|
|
def fetch_literal(self):
|
|
self.fetch_block_scalar(style='|')
|
|
|
|
def fetch_folded(self):
|
|
self.fetch_block_scalar(style='>')
|
|
|
|
def fetch_block_scalar(self, style):
|
|
|
|
# A simple key may follow a block scalar.
|
|
self.allow_simple_key = True
|
|
|
|
# Reset possible simple key on the current level.
|
|
self.remove_possible_simple_key()
|
|
|
|
# Scan and add SCALAR.
|
|
self.tokens.append(self.scan_block_scalar(style))
|
|
|
|
def fetch_single(self):
|
|
self.fetch_flow_scalar(style='\'')
|
|
|
|
def fetch_double(self):
|
|
self.fetch_flow_scalar(style='"')
|
|
|
|
def fetch_flow_scalar(self, style):
|
|
|
|
# A flow scalar could be a simple key.
|
|
self.save_possible_simple_key()
|
|
|
|
# No simple keys after flow scalars.
|
|
self.allow_simple_key = False
|
|
|
|
# Scan and add SCALAR.
|
|
self.tokens.append(self.scan_flow_scalar(style))
|
|
|
|
def fetch_plain(self):
|
|
|
|
# A plain scalar could be a simple key.
|
|
self.save_possible_simple_key()
|
|
|
|
# No simple keys after plain scalars. But note that `scan_plain` will
|
|
# change this flag if the scan is finished at the beginning of the
|
|
# line.
|
|
self.allow_simple_key = False
|
|
|
|
# Scan and add SCALAR. May change `allow_simple_key`.
|
|
self.tokens.append(self.scan_plain())
|
|
|
|
# Checkers.
|
|
|
|
def check_directive(self):
|
|
|
|
# DIRECTIVE: ^ '%' ...
|
|
# The '%' indicator is already checked.
|
|
if self.column == 0:
|
|
return True
|
|
|
|
def check_document_start(self):
|
|
|
|
# DOCUMENT-START: ^ '---' (' '|'\n')
|
|
if self.column == 0:
|
|
if self.prefix(3) == '---' \
|
|
and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
|
|
return True
|
|
|
|
def check_document_end(self):
|
|
|
|
# DOCUMENT-END: ^ '...' (' '|'\n')
|
|
if self.column == 0:
|
|
if self.prefix(3) == '...' \
|
|
and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
|
|
return True
|
|
|
|
def check_block_entry(self):
|
|
|
|
# BLOCK-ENTRY: '-' (' '|'\n')
|
|
return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
|
|
|
|
def check_key(self):
|
|
|
|
# KEY(flow context): '?'
|
|
if self.flow_level:
|
|
return True
|
|
|
|
# KEY(block context): '?' (' '|'\n')
|
|
else:
|
|
return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
|
|
|
|
def check_value(self):
|
|
|
|
# VALUE(flow context): ':'
|
|
if self.flow_level:
|
|
return True
|
|
|
|
# VALUE(block context): ':' (' '|'\n')
|
|
else:
|
|
return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
|
|
|
|
def check_plain(self):
|
|
|
|
# A plain scalar may start with any non-space character except:
|
|
# '-', '?', ':', ',', '[', ']', '{', '}',
|
|
# '#', '&', '*', '!', '|', '>', '\'', '\"',
|
|
# '%', '@', '`'.
|
|
#
|
|
# It may also start with
|
|
# '-', '?', ':'
|
|
# if it is followed by a non-space character.
|
|
#
|
|
# Note that we limit the last rule to the block context (except the
|
|
# '-' character) because we want the flow context to be space
|
|
# independent.
|
|
ch = self.peek()
|
|
return ch not in '\0 \t\r\n\x85\u2028\u2029-?:,[]{}#&*!|>\'\"%@`' \
|
|
or (self.peek(1) not in '\0 \t\r\n\x85\u2028\u2029'
|
|
and (ch == '-' or (not self.flow_level and ch in '?:')))
|
|
|
|
# Scanners.
|
|
|
|
def scan_to_next_token(self):
|
|
# We ignore spaces, line breaks and comments.
|
|
# If we find a line break in the block context, we set the flag
|
|
# `allow_simple_key` on.
|
|
# The byte order mark is stripped if it's the first character in the
|
|
# stream. We do not yet support BOM inside the stream as the
|
|
# specification requires. Any such mark will be considered as a part
|
|
# of the document.
|
|
#
|
|
# TODO: We need to make tab handling rules more sane. A good rule is
|
|
# Tabs cannot precede tokens
|
|
# BLOCK-SEQUENCE-START, BLOCK-MAPPING-START, BLOCK-END,
|
|
# KEY(block), VALUE(block), BLOCK-ENTRY
|
|
# So the checking code is
|
|
# if <TAB>:
|
|
# self.allow_simple_keys = False
|
|
# We also need to add the check for `allow_simple_keys == True` to
|
|
# `unwind_indent` before issuing BLOCK-END.
|
|
# Scanners for block, flow, and plain scalars need to be modified.
|
|
|
|
if self.index == 0 and self.peek() == '\uFEFF':
|
|
self.forward()
|
|
found = False
|
|
while not found:
|
|
while self.peek() == ' ':
|
|
self.forward()
|
|
if self.peek() == '#':
|
|
while self.peek() not in '\0\r\n\x85\u2028\u2029':
|
|
self.forward()
|
|
if self.scan_line_break():
|
|
if not self.flow_level:
|
|
self.allow_simple_key = True
|
|
else:
|
|
found = True
|
|
|
|
def scan_directive(self):
|
|
# See the specification for details.
|
|
start_mark = self.get_mark()
|
|
self.forward()
|
|
name = self.scan_directive_name(start_mark)
|
|
value = None
|
|
if name == 'YAML':
|
|
value = self.scan_yaml_directive_value(start_mark)
|
|
end_mark = self.get_mark()
|
|
elif name == 'TAG':
|
|
value = self.scan_tag_directive_value(start_mark)
|
|
end_mark = self.get_mark()
|
|
else:
|
|
end_mark = self.get_mark()
|
|
while self.peek() not in '\0\r\n\x85\u2028\u2029':
|
|
self.forward()
|
|
self.scan_directive_ignored_line(start_mark)
|
|
return DirectiveToken(name, value, start_mark, end_mark)
|
|
|
|
def scan_directive_name(self, start_mark):
|
|
# See the specification for details.
|
|
length = 0
|
|
ch = self.peek(length)
|
|
while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' \
|
|
or ch in '-_':
|
|
length += 1
|
|
ch = self.peek(length)
|
|
if not length:
|
|
raise ScannerError("while scanning a directive", start_mark,
|
|
"expected alphabetic or numeric character, but found %r"
|
|
% ch, self.get_mark())
|
|
value = self.prefix(length)
|
|
self.forward(length)
|
|
ch = self.peek()
|
|
if ch not in '\0 \r\n\x85\u2028\u2029':
|
|
raise ScannerError("while scanning a directive", start_mark,
|
|
"expected alphabetic or numeric character, but found %r"
|
|
% ch, self.get_mark())
|
|
return value
|
|
|
|
def scan_yaml_directive_value(self, start_mark):
|
|
# See the specification for details.
|
|
while self.peek() == ' ':
|
|
self.forward()
|
|
major = self.scan_yaml_directive_number(start_mark)
|
|
if self.peek() != '.':
|
|
raise ScannerError("while scanning a directive", start_mark,
|
|
"expected a digit or '.', but found %r" % self.peek(),
|
|
self.get_mark())
|
|
self.forward()
|
|
minor = self.scan_yaml_directive_number(start_mark)
|
|
if self.peek() not in '\0 \r\n\x85\u2028\u2029':
|
|
raise ScannerError("while scanning a directive", start_mark,
|
|
"expected a digit or ' ', but found %r" % self.peek(),
|
|
self.get_mark())
|
|
return (major, minor)
|
|
|
|
def scan_yaml_directive_number(self, start_mark):
|
|
# See the specification for details.
|
|
ch = self.peek()
|
|
if not ('0' <= ch <= '9'):
|
|
raise ScannerError("while scanning a directive", start_mark,
|
|
"expected a digit, but found %r" % ch, self.get_mark())
|
|
length = 0
|
|
while '0' <= self.peek(length) <= '9':
|
|
length += 1
|
|
value = int(self.prefix(length))
|
|
self.forward(length)
|
|
return value
|
|
|
|
def scan_tag_directive_value(self, start_mark):
|
|
# See the specification for details.
|
|
while self.peek() == ' ':
|
|
self.forward()
|
|
handle = self.scan_tag_directive_handle(start_mark)
|
|
while self.peek() == ' ':
|
|
self.forward()
|
|
prefix = self.scan_tag_directive_prefix(start_mark)
|
|
return (handle, prefix)
|
|
|
|
def scan_tag_directive_handle(self, start_mark):
|
|
# See the specification for details.
|
|
value = self.scan_tag_handle('directive', start_mark)
|
|
ch = self.peek()
|
|
if ch != ' ':
|
|
raise ScannerError("while scanning a directive", start_mark,
|
|
"expected ' ', but found %r" % ch, self.get_mark())
|
|
return value
|
|
|
|
def scan_tag_directive_prefix(self, start_mark):
|
|
# See the specification for details.
|
|
value = self.scan_tag_uri('directive', start_mark)
|
|
ch = self.peek()
|
|
if ch not in '\0 \r\n\x85\u2028\u2029':
|
|
raise ScannerError("while scanning a directive", start_mark,
|
|
"expected ' ', but found %r" % ch, self.get_mark())
|
|
return value
|
|
|
|
def scan_directive_ignored_line(self, start_mark):
|
|
# See the specification for details.
|
|
while self.peek() == ' ':
|
|
self.forward()
|
|
if self.peek() == '#':
|
|
while self.peek() not in '\0\r\n\x85\u2028\u2029':
|
|
self.forward()
|
|
ch = self.peek()
|
|
if ch not in '\0\r\n\x85\u2028\u2029':
|
|
raise ScannerError("while scanning a directive", start_mark,
|
|
"expected a comment or a line break, but found %r"
|
|
% ch, self.get_mark())
|
|
self.scan_line_break()
|
|
|
|
def scan_anchor(self, TokenClass):
|
|
# The specification does not restrict characters for anchors and
|
|
# aliases. This may lead to problems, for instance, the document:
|
|
# [ *alias, value ]
|
|
# can be interpreted in two ways, as
|
|
# [ "value" ]
|
|
# and
|
|
# [ *alias , "value" ]
|
|
# Therefore we restrict aliases to numbers and ASCII letters.
|
|
start_mark = self.get_mark()
|
|
indicator = self.peek()
|
|
if indicator == '*':
|
|
name = 'alias'
|
|
else:
|
|
name = 'anchor'
|
|
self.forward()
|
|
length = 0
|
|
ch = self.peek(length)
|
|
while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' \
|
|
or ch in '-_':
|
|
length += 1
|
|
ch = self.peek(length)
|
|
if not length:
|
|
raise ScannerError("while scanning an %s" % name, start_mark,
|
|
"expected alphabetic or numeric character, but found %r"
|
|
% ch, self.get_mark())
|
|
value = self.prefix(length)
|
|
self.forward(length)
|
|
ch = self.peek()
|
|
if ch not in '\0 \t\r\n\x85\u2028\u2029?:,]}%@`':
|
|
raise ScannerError("while scanning an %s" % name, start_mark,
|
|
"expected alphabetic or numeric character, but found %r"
|
|
% ch, self.get_mark())
|
|
end_mark = self.get_mark()
|
|
return TokenClass(value, start_mark, end_mark)
|
|
|
|
def scan_tag(self):
|
|
# See the specification for details.
|
|
start_mark = self.get_mark()
|
|
ch = self.peek(1)
|
|
if ch == '<':
|
|
handle = None
|
|
self.forward(2)
|
|
suffix = self.scan_tag_uri('tag', start_mark)
|
|
if self.peek() != '>':
|
|
raise ScannerError("while parsing a tag", start_mark,
|
|
"expected '>', but found %r" % self.peek(),
|
|
self.get_mark())
|
|
self.forward()
|
|
elif ch in '\0 \t\r\n\x85\u2028\u2029':
|
|
handle = None
|
|
suffix = '!'
|
|
self.forward()
|
|
else:
|
|
length = 1
|
|
use_handle = False
|
|
while ch not in '\0 \r\n\x85\u2028\u2029':
|
|
if ch == '!':
|
|
use_handle = True
|
|
break
|
|
length += 1
|
|
ch = self.peek(length)
|
|
handle = '!'
|
|
if use_handle:
|
|
handle = self.scan_tag_handle('tag', start_mark)
|
|
else:
|
|
handle = '!'
|
|
self.forward()
|
|
suffix = self.scan_tag_uri('tag', start_mark)
|
|
ch = self.peek()
|
|
if ch not in '\0 \r\n\x85\u2028\u2029':
|
|
raise ScannerError("while scanning a tag", start_mark,
|
|
"expected ' ', but found %r" % ch, self.get_mark())
|
|
value = (handle, suffix)
|
|
end_mark = self.get_mark()
|
|
return TagToken(value, start_mark, end_mark)
|
|
|
|
def scan_block_scalar(self, style):
|
|
# See the specification for details.
|
|
|
|
if style == '>':
|
|
folded = True
|
|
else:
|
|
folded = False
|
|
|
|
chunks = []
|
|
start_mark = self.get_mark()
|
|
|
|
# Scan the header.
|
|
self.forward()
|
|
chomping, increment = self.scan_block_scalar_indicators(start_mark)
|
|
self.scan_block_scalar_ignored_line(start_mark)
|
|
|
|
# Determine the indentation level and go to the first non-empty line.
|
|
min_indent = self.indent+1
|
|
if min_indent < 1:
|
|
min_indent = 1
|
|
if increment is None:
|
|
breaks, max_indent, end_mark = self.scan_block_scalar_indentation()
|
|
indent = max(min_indent, max_indent)
|
|
else:
|
|
indent = min_indent+increment-1
|
|
breaks, end_mark = self.scan_block_scalar_breaks(indent)
|
|
line_break = ''
|
|
|
|
# Scan the inner part of the block scalar.
|
|
while self.column == indent and self.peek() != '\0':
|
|
chunks.extend(breaks)
|
|
leading_non_space = self.peek() not in ' \t'
|
|
length = 0
|
|
while self.peek(length) not in '\0\r\n\x85\u2028\u2029':
|
|
length += 1
|
|
chunks.append(self.prefix(length))
|
|
self.forward(length)
|
|
line_break = self.scan_line_break()
|
|
breaks, end_mark = self.scan_block_scalar_breaks(indent)
|
|
if self.column == indent and self.peek() != '\0':
|
|
|
|
# Unfortunately, folding rules are ambiguous.
|
|
#
|
|
# This is the folding according to the specification:
|
|
|
|
if folded and line_break == '\n' \
|
|
and leading_non_space and self.peek() not in ' \t':
|
|
if not breaks:
|
|
chunks.append(' ')
|
|
else:
|
|
chunks.append(line_break)
|
|
|
|
# This is Clark Evans's interpretation (also in the spec
|
|
# examples):
|
|
#
|
|
#if folded and line_break == '\n':
|
|
# if not breaks:
|
|
# if self.peek() not in ' \t':
|
|
# chunks.append(' ')
|
|
# else:
|
|
# chunks.append(line_break)
|
|
#else:
|
|
# chunks.append(line_break)
|
|
else:
|
|
break
|
|
|
|
# Chomp the tail.
|
|
if chomping is not False:
|
|
chunks.append(line_break)
|
|
if chomping is True:
|
|
chunks.extend(breaks)
|
|
|
|
# We are done.
|
|
return ScalarToken(''.join(chunks), False, start_mark, end_mark,
|
|
style)
|
|
|
|
def scan_block_scalar_indicators(self, start_mark):
|
|
# See the specification for details.
|
|
chomping = None
|
|
increment = None
|
|
ch = self.peek()
|
|
if ch in '+-':
|
|
if ch == '+':
|
|
chomping = True
|
|
else:
|
|
chomping = False
|
|
self.forward()
|
|
ch = self.peek()
|
|
if ch in '0123456789':
|
|
increment = int(ch)
|
|
if increment == 0:
|
|
raise ScannerError("while scanning a block scalar", start_mark,
|
|
"expected indentation indicator in the range 1-9, but found 0",
|
|
self.get_mark())
|
|
self.forward()
|
|
elif ch in '0123456789':
|
|
increment = int(ch)
|
|
if increment == 0:
|
|
raise ScannerError("while scanning a block scalar", start_mark,
|
|
"expected indentation indicator in the range 1-9, but found 0",
|
|
self.get_mark())
|
|
self.forward()
|
|
ch = self.peek()
|
|
if ch in '+-':
|
|
if ch == '+':
|
|
chomping = True
|
|
else:
|
|
chomping = False
|
|
self.forward()
|
|
ch = self.peek()
|
|
if ch not in '\0 \r\n\x85\u2028\u2029':
|
|
raise ScannerError("while scanning a block scalar", start_mark,
|
|
"expected chomping or indentation indicators, but found %r"
|
|
% ch, self.get_mark())
|
|
return chomping, increment
|
|
|
|
def scan_block_scalar_ignored_line(self, start_mark):
|
|
# See the specification for details.
|
|
while self.peek() == ' ':
|
|
self.forward()
|
|
if self.peek() == '#':
|
|
while self.peek() not in '\0\r\n\x85\u2028\u2029':
|
|
self.forward()
|
|
ch = self.peek()
|
|
if ch not in '\0\r\n\x85\u2028\u2029':
|
|
raise ScannerError("while scanning a block scalar", start_mark,
|
|
"expected a comment or a line break, but found %r" % ch,
|
|
self.get_mark())
|
|
self.scan_line_break()
|
|
|
|
def scan_block_scalar_indentation(self):
|
|
# See the specification for details.
|
|
chunks = []
|
|
max_indent = 0
|
|
end_mark = self.get_mark()
|
|
while self.peek() in ' \r\n\x85\u2028\u2029':
|
|
if self.peek() != ' ':
|
|
chunks.append(self.scan_line_break())
|
|
end_mark = self.get_mark()
|
|
else:
|
|
self.forward()
|
|
if self.column > max_indent:
|
|
max_indent = self.column
|
|
return chunks, max_indent, end_mark
|
|
|
|
def scan_block_scalar_breaks(self, indent):
|
|
# See the specification for details.
|
|
chunks = []
|
|
end_mark = self.get_mark()
|
|
while self.column < indent and self.peek() == ' ':
|
|
self.forward()
|
|
while self.peek() in '\r\n\x85\u2028\u2029':
|
|
chunks.append(self.scan_line_break())
|
|
end_mark = self.get_mark()
|
|
while self.column < indent and self.peek() == ' ':
|
|
self.forward()
|
|
return chunks, end_mark
|
|
|
|
def scan_flow_scalar(self, style):
|
|
# See the specification for details.
|
|
# Note that we loose indentation rules for quoted scalars. Quoted
|
|
# scalars don't need to adhere indentation because " and ' clearly
|
|
# mark the beginning and the end of them. Therefore we are less
|
|
# restrictive then the specification requires. We only need to check
|
|
# that document separators are not included in scalars.
|
|
if style == '"':
|
|
double = True
|
|
else:
|
|
double = False
|
|
chunks = []
|
|
start_mark = self.get_mark()
|
|
quote = self.peek()
|
|
self.forward()
|
|
chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
|
|
while self.peek() != quote:
|
|
chunks.extend(self.scan_flow_scalar_spaces(double, start_mark))
|
|
chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
|
|
self.forward()
|
|
end_mark = self.get_mark()
|
|
return ScalarToken(''.join(chunks), False, start_mark, end_mark,
|
|
style)
|
|
|
|
ESCAPE_REPLACEMENTS = {
|
|
'0': '\0',
|
|
'a': '\x07',
|
|
'b': '\x08',
|
|
't': '\x09',
|
|
'\t': '\x09',
|
|
'n': '\x0A',
|
|
'v': '\x0B',
|
|
'f': '\x0C',
|
|
'r': '\x0D',
|
|
'e': '\x1B',
|
|
' ': '\x20',
|
|
'\"': '\"',
|
|
'\\': '\\',
|
|
'/': '/',
|
|
'N': '\x85',
|
|
'_': '\xA0',
|
|
'L': '\u2028',
|
|
'P': '\u2029',
|
|
}
|
|
|
|
ESCAPE_CODES = {
|
|
'x': 2,
|
|
'u': 4,
|
|
'U': 8,
|
|
}
|
|
|
|
def scan_flow_scalar_non_spaces(self, double, start_mark):
|
|
# See the specification for details.
|
|
chunks = []
|
|
while True:
|
|
length = 0
|
|
while self.peek(length) not in '\'\"\\\0 \t\r\n\x85\u2028\u2029':
|
|
length += 1
|
|
if length:
|
|
chunks.append(self.prefix(length))
|
|
self.forward(length)
|
|
ch = self.peek()
|
|
if not double and ch == '\'' and self.peek(1) == '\'':
|
|
chunks.append('\'')
|
|
self.forward(2)
|
|
elif (double and ch == '\'') or (not double and ch in '\"\\'):
|
|
chunks.append(ch)
|
|
self.forward()
|
|
elif double and ch == '\\':
|
|
self.forward()
|
|
ch = self.peek()
|
|
if ch in self.ESCAPE_REPLACEMENTS:
|
|
chunks.append(self.ESCAPE_REPLACEMENTS[ch])
|
|
self.forward()
|
|
elif ch in self.ESCAPE_CODES:
|
|
length = self.ESCAPE_CODES[ch]
|
|
self.forward()
|
|
for k in range(length):
|
|
if self.peek(k) not in '0123456789ABCDEFabcdef':
|
|
raise ScannerError("while scanning a double-quoted scalar", start_mark,
|
|
"expected escape sequence of %d hexadecimal numbers, but found %r" %
|
|
(length, self.peek(k)), self.get_mark())
|
|
code = int(self.prefix(length), 16)
|
|
chunks.append(chr(code))
|
|
self.forward(length)
|
|
elif ch in '\r\n\x85\u2028\u2029':
|
|
self.scan_line_break()
|
|
chunks.extend(self.scan_flow_scalar_breaks(double, start_mark))
|
|
else:
|
|
raise ScannerError("while scanning a double-quoted scalar", start_mark,
|
|
"found unknown escape character %r" % ch, self.get_mark())
|
|
else:
|
|
return chunks
|
|
|
|
def scan_flow_scalar_spaces(self, double, start_mark):
|
|
# See the specification for details.
|
|
chunks = []
|
|
length = 0
|
|
while self.peek(length) in ' \t':
|
|
length += 1
|
|
whitespaces = self.prefix(length)
|
|
self.forward(length)
|
|
ch = self.peek()
|
|
if ch == '\0':
|
|
raise ScannerError("while scanning a quoted scalar", start_mark,
|
|
"found unexpected end of stream", self.get_mark())
|
|
elif ch in '\r\n\x85\u2028\u2029':
|
|
line_break = self.scan_line_break()
|
|
breaks = self.scan_flow_scalar_breaks(double, start_mark)
|
|
if line_break != '\n':
|
|
chunks.append(line_break)
|
|
elif not breaks:
|
|
chunks.append(' ')
|
|
chunks.extend(breaks)
|
|
else:
|
|
chunks.append(whitespaces)
|
|
return chunks
|
|
|
|
def scan_flow_scalar_breaks(self, double, start_mark):
|
|
# See the specification for details.
|
|
chunks = []
|
|
while True:
|
|
# Instead of checking indentation, we check for document
|
|
# separators.
|
|
prefix = self.prefix(3)
|
|
if (prefix == '---' or prefix == '...') \
|
|
and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
|
|
raise ScannerError("while scanning a quoted scalar", start_mark,
|
|
"found unexpected document separator", self.get_mark())
|
|
while self.peek() in ' \t':
|
|
self.forward()
|
|
if self.peek() in '\r\n\x85\u2028\u2029':
|
|
chunks.append(self.scan_line_break())
|
|
else:
|
|
return chunks
|
|
|
|
def scan_plain(self):
|
|
# See the specification for details.
|
|
# We add an additional restriction for the flow context:
|
|
# plain scalars in the flow context cannot contain ',' or '?'.
|
|
# We also keep track of the `allow_simple_key` flag here.
|
|
# Indentation rules are loosed for the flow context.
|
|
chunks = []
|
|
start_mark = self.get_mark()
|
|
end_mark = start_mark
|
|
indent = self.indent+1
|
|
# We allow zero indentation for scalars, but then we need to check for
|
|
# document separators at the beginning of the line.
|
|
#if indent == 0:
|
|
# indent = 1
|
|
spaces = []
|
|
while True:
|
|
length = 0
|
|
if self.peek() == '#':
|
|
break
|
|
while True:
|
|
ch = self.peek(length)
|
|
if ch in '\0 \t\r\n\x85\u2028\u2029' \
|
|
or (ch == ':' and
|
|
self.peek(length+1) in '\0 \t\r\n\x85\u2028\u2029'
|
|
+ (u',[]{}' if self.flow_level else u''))\
|
|
or (self.flow_level and ch in ',?[]{}'):
|
|
break
|
|
length += 1
|
|
if length == 0:
|
|
break
|
|
self.allow_simple_key = False
|
|
chunks.extend(spaces)
|
|
chunks.append(self.prefix(length))
|
|
self.forward(length)
|
|
end_mark = self.get_mark()
|
|
spaces = self.scan_plain_spaces(indent, start_mark)
|
|
if not spaces or self.peek() == '#' \
|
|
or (not self.flow_level and self.column < indent):
|
|
break
|
|
return ScalarToken(''.join(chunks), True, start_mark, end_mark)
|
|
|
|
def scan_plain_spaces(self, indent, start_mark):
|
|
# See the specification for details.
|
|
# The specification is really confusing about tabs in plain scalars.
|
|
# We just forbid them completely. Do not use tabs in YAML!
|
|
chunks = []
|
|
length = 0
|
|
while self.peek(length) in ' ':
|
|
length += 1
|
|
whitespaces = self.prefix(length)
|
|
self.forward(length)
|
|
ch = self.peek()
|
|
if ch in '\r\n\x85\u2028\u2029':
|
|
line_break = self.scan_line_break()
|
|
self.allow_simple_key = True
|
|
prefix = self.prefix(3)
|
|
if (prefix == '---' or prefix == '...') \
|
|
and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
|
|
return
|
|
breaks = []
|
|
while self.peek() in ' \r\n\x85\u2028\u2029':
|
|
if self.peek() == ' ':
|
|
self.forward()
|
|
else:
|
|
breaks.append(self.scan_line_break())
|
|
prefix = self.prefix(3)
|
|
if (prefix == '---' or prefix == '...') \
|
|
and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
|
|
return
|
|
if line_break != '\n':
|
|
chunks.append(line_break)
|
|
elif not breaks:
|
|
chunks.append(' ')
|
|
chunks.extend(breaks)
|
|
elif whitespaces:
|
|
chunks.append(whitespaces)
|
|
return chunks
|
|
|
|
def scan_tag_handle(self, name, start_mark):
|
|
# See the specification for details.
|
|
# For some strange reasons, the specification does not allow '_' in
|
|
# tag handles. I have allowed it anyway.
|
|
ch = self.peek()
|
|
if ch != '!':
|
|
raise ScannerError("while scanning a %s" % name, start_mark,
|
|
"expected '!', but found %r" % ch, self.get_mark())
|
|
length = 1
|
|
ch = self.peek(length)
|
|
if ch != ' ':
|
|
while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' \
|
|
or ch in '-_':
|
|
length += 1
|
|
ch = self.peek(length)
|
|
if ch != '!':
|
|
self.forward(length)
|
|
raise ScannerError("while scanning a %s" % name, start_mark,
|
|
"expected '!', but found %r" % ch, self.get_mark())
|
|
length += 1
|
|
value = self.prefix(length)
|
|
self.forward(length)
|
|
return value
|
|
|
|
def scan_tag_uri(self, name, start_mark):
|
|
# See the specification for details.
|
|
# Note: we do not check if URI is well-formed.
|
|
chunks = []
|
|
length = 0
|
|
ch = self.peek(length)
|
|
while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' \
|
|
or ch in '-;/?:@&=+$,_.!~*\'()[]%':
|
|
if ch == '%':
|
|
chunks.append(self.prefix(length))
|
|
self.forward(length)
|
|
length = 0
|
|
chunks.append(self.scan_uri_escapes(name, start_mark))
|
|
else:
|
|
length += 1
|
|
ch = self.peek(length)
|
|
if length:
|
|
chunks.append(self.prefix(length))
|
|
self.forward(length)
|
|
length = 0
|
|
if not chunks:
|
|
raise ScannerError("while parsing a %s" % name, start_mark,
|
|
"expected URI, but found %r" % ch, self.get_mark())
|
|
return ''.join(chunks)
|
|
|
|
def scan_uri_escapes(self, name, start_mark):
|
|
# See the specification for details.
|
|
codes = []
|
|
mark = self.get_mark()
|
|
while self.peek() == '%':
|
|
self.forward()
|
|
for k in range(2):
|
|
if self.peek(k) not in '0123456789ABCDEFabcdef':
|
|
raise ScannerError("while scanning a %s" % name, start_mark,
|
|
"expected URI escape sequence of 2 hexadecimal numbers, but found %r"
|
|
% self.peek(k), self.get_mark())
|
|
codes.append(int(self.prefix(2), 16))
|
|
self.forward(2)
|
|
try:
|
|
value = bytes(codes).decode('utf-8')
|
|
except UnicodeDecodeError as exc:
|
|
raise ScannerError("while scanning a %s" % name, start_mark, str(exc), mark)
|
|
return value
|
|
|
|
def scan_line_break(self):
|
|
# Transforms:
|
|
# '\r\n' : '\n'
|
|
# '\r' : '\n'
|
|
# '\n' : '\n'
|
|
# '\x85' : '\n'
|
|
# '\u2028' : '\u2028'
|
|
# '\u2029 : '\u2029'
|
|
# default : ''
|
|
ch = self.peek()
|
|
if ch in '\r\n\x85':
|
|
if self.prefix(2) == '\r\n':
|
|
self.forward(2)
|
|
else:
|
|
self.forward()
|
|
return '\n'
|
|
elif ch in '\u2028\u2029':
|
|
self.forward()
|
|
return ch
|
|
return ''
|