503 lines
17 KiB
Python
503 lines
17 KiB
Python
#------------------------------------------------------------------------------
|
|
# pycparser: c_generator.py
|
|
#
|
|
# C code generator from pycparser AST nodes.
|
|
#
|
|
# Eli Bendersky [https://eli.thegreenplace.net/]
|
|
# License: BSD
|
|
#------------------------------------------------------------------------------
|
|
from . import c_ast
|
|
|
|
|
|
class CGenerator(object):
|
|
""" Uses the same visitor pattern as c_ast.NodeVisitor, but modified to
|
|
return a value from each visit method, using string accumulation in
|
|
generic_visit.
|
|
"""
|
|
def __init__(self, reduce_parentheses=False):
|
|
""" Constructs C-code generator
|
|
|
|
reduce_parentheses:
|
|
if True, eliminates needless parentheses on binary operators
|
|
"""
|
|
# Statements start with indentation of self.indent_level spaces, using
|
|
# the _make_indent method.
|
|
self.indent_level = 0
|
|
self.reduce_parentheses = reduce_parentheses
|
|
|
|
def _make_indent(self):
|
|
return ' ' * self.indent_level
|
|
|
|
def visit(self, node):
|
|
method = 'visit_' + node.__class__.__name__
|
|
return getattr(self, method, self.generic_visit)(node)
|
|
|
|
def generic_visit(self, node):
|
|
if node is None:
|
|
return ''
|
|
else:
|
|
return ''.join(self.visit(c) for c_name, c in node.children())
|
|
|
|
def visit_Constant(self, n):
|
|
return n.value
|
|
|
|
def visit_ID(self, n):
|
|
return n.name
|
|
|
|
def visit_Pragma(self, n):
|
|
ret = '#pragma'
|
|
if n.string:
|
|
ret += ' ' + n.string
|
|
return ret
|
|
|
|
def visit_ArrayRef(self, n):
|
|
arrref = self._parenthesize_unless_simple(n.name)
|
|
return arrref + '[' + self.visit(n.subscript) + ']'
|
|
|
|
def visit_StructRef(self, n):
|
|
sref = self._parenthesize_unless_simple(n.name)
|
|
return sref + n.type + self.visit(n.field)
|
|
|
|
def visit_FuncCall(self, n):
|
|
fref = self._parenthesize_unless_simple(n.name)
|
|
return fref + '(' + self.visit(n.args) + ')'
|
|
|
|
def visit_UnaryOp(self, n):
|
|
if n.op == 'sizeof':
|
|
# Always parenthesize the argument of sizeof since it can be
|
|
# a name.
|
|
return 'sizeof(%s)' % self.visit(n.expr)
|
|
else:
|
|
operand = self._parenthesize_unless_simple(n.expr)
|
|
if n.op == 'p++':
|
|
return '%s++' % operand
|
|
elif n.op == 'p--':
|
|
return '%s--' % operand
|
|
else:
|
|
return '%s%s' % (n.op, operand)
|
|
|
|
# Precedence map of binary operators:
|
|
precedence_map = {
|
|
# Should be in sync with c_parser.CParser.precedence
|
|
# Higher numbers are stronger binding
|
|
'||': 0, # weakest binding
|
|
'&&': 1,
|
|
'|': 2,
|
|
'^': 3,
|
|
'&': 4,
|
|
'==': 5, '!=': 5,
|
|
'>': 6, '>=': 6, '<': 6, '<=': 6,
|
|
'>>': 7, '<<': 7,
|
|
'+': 8, '-': 8,
|
|
'*': 9, '/': 9, '%': 9 # strongest binding
|
|
}
|
|
|
|
def visit_BinaryOp(self, n):
|
|
# Note: all binary operators are left-to-right associative
|
|
#
|
|
# If `n.left.op` has a stronger or equally binding precedence in
|
|
# comparison to `n.op`, no parenthesis are needed for the left:
|
|
# e.g., `(a*b) + c` is equivalent to `a*b + c`, as well as
|
|
# `(a+b) - c` is equivalent to `a+b - c` (same precedence).
|
|
# If the left operator is weaker binding than the current, then
|
|
# parentheses are necessary:
|
|
# e.g., `(a+b) * c` is NOT equivalent to `a+b * c`.
|
|
lval_str = self._parenthesize_if(
|
|
n.left,
|
|
lambda d: not (self._is_simple_node(d) or
|
|
self.reduce_parentheses and isinstance(d, c_ast.BinaryOp) and
|
|
self.precedence_map[d.op] >= self.precedence_map[n.op]))
|
|
# If `n.right.op` has a stronger -but not equal- binding precedence,
|
|
# parenthesis can be omitted on the right:
|
|
# e.g., `a + (b*c)` is equivalent to `a + b*c`.
|
|
# If the right operator is weaker or equally binding, then parentheses
|
|
# are necessary:
|
|
# e.g., `a * (b+c)` is NOT equivalent to `a * b+c` and
|
|
# `a - (b+c)` is NOT equivalent to `a - b+c` (same precedence).
|
|
rval_str = self._parenthesize_if(
|
|
n.right,
|
|
lambda d: not (self._is_simple_node(d) or
|
|
self.reduce_parentheses and isinstance(d, c_ast.BinaryOp) and
|
|
self.precedence_map[d.op] > self.precedence_map[n.op]))
|
|
return '%s %s %s' % (lval_str, n.op, rval_str)
|
|
|
|
def visit_Assignment(self, n):
|
|
rval_str = self._parenthesize_if(
|
|
n.rvalue,
|
|
lambda n: isinstance(n, c_ast.Assignment))
|
|
return '%s %s %s' % (self.visit(n.lvalue), n.op, rval_str)
|
|
|
|
def visit_IdentifierType(self, n):
|
|
return ' '.join(n.names)
|
|
|
|
def _visit_expr(self, n):
|
|
if isinstance(n, c_ast.InitList):
|
|
return '{' + self.visit(n) + '}'
|
|
elif isinstance(n, c_ast.ExprList):
|
|
return '(' + self.visit(n) + ')'
|
|
else:
|
|
return self.visit(n)
|
|
|
|
def visit_Decl(self, n, no_type=False):
|
|
# no_type is used when a Decl is part of a DeclList, where the type is
|
|
# explicitly only for the first declaration in a list.
|
|
#
|
|
s = n.name if no_type else self._generate_decl(n)
|
|
if n.bitsize: s += ' : ' + self.visit(n.bitsize)
|
|
if n.init:
|
|
s += ' = ' + self._visit_expr(n.init)
|
|
return s
|
|
|
|
def visit_DeclList(self, n):
|
|
s = self.visit(n.decls[0])
|
|
if len(n.decls) > 1:
|
|
s += ', ' + ', '.join(self.visit_Decl(decl, no_type=True)
|
|
for decl in n.decls[1:])
|
|
return s
|
|
|
|
def visit_Typedef(self, n):
|
|
s = ''
|
|
if n.storage: s += ' '.join(n.storage) + ' '
|
|
s += self._generate_type(n.type)
|
|
return s
|
|
|
|
def visit_Cast(self, n):
|
|
s = '(' + self._generate_type(n.to_type, emit_declname=False) + ')'
|
|
return s + ' ' + self._parenthesize_unless_simple(n.expr)
|
|
|
|
def visit_ExprList(self, n):
|
|
visited_subexprs = []
|
|
for expr in n.exprs:
|
|
visited_subexprs.append(self._visit_expr(expr))
|
|
return ', '.join(visited_subexprs)
|
|
|
|
def visit_InitList(self, n):
|
|
visited_subexprs = []
|
|
for expr in n.exprs:
|
|
visited_subexprs.append(self._visit_expr(expr))
|
|
return ', '.join(visited_subexprs)
|
|
|
|
def visit_Enum(self, n):
|
|
return self._generate_struct_union_enum(n, name='enum')
|
|
|
|
def visit_Alignas(self, n):
|
|
return '_Alignas({})'.format(self.visit(n.alignment))
|
|
|
|
def visit_Enumerator(self, n):
|
|
if not n.value:
|
|
return '{indent}{name},\n'.format(
|
|
indent=self._make_indent(),
|
|
name=n.name,
|
|
)
|
|
else:
|
|
return '{indent}{name} = {value},\n'.format(
|
|
indent=self._make_indent(),
|
|
name=n.name,
|
|
value=self.visit(n.value),
|
|
)
|
|
|
|
def visit_FuncDef(self, n):
|
|
decl = self.visit(n.decl)
|
|
self.indent_level = 0
|
|
body = self.visit(n.body)
|
|
if n.param_decls:
|
|
knrdecls = ';\n'.join(self.visit(p) for p in n.param_decls)
|
|
return decl + '\n' + knrdecls + ';\n' + body + '\n'
|
|
else:
|
|
return decl + '\n' + body + '\n'
|
|
|
|
def visit_FileAST(self, n):
|
|
s = ''
|
|
for ext in n.ext:
|
|
if isinstance(ext, c_ast.FuncDef):
|
|
s += self.visit(ext)
|
|
elif isinstance(ext, c_ast.Pragma):
|
|
s += self.visit(ext) + '\n'
|
|
else:
|
|
s += self.visit(ext) + ';\n'
|
|
return s
|
|
|
|
def visit_Compound(self, n):
|
|
s = self._make_indent() + '{\n'
|
|
self.indent_level += 2
|
|
if n.block_items:
|
|
s += ''.join(self._generate_stmt(stmt) for stmt in n.block_items)
|
|
self.indent_level -= 2
|
|
s += self._make_indent() + '}\n'
|
|
return s
|
|
|
|
def visit_CompoundLiteral(self, n):
|
|
return '(' + self.visit(n.type) + '){' + self.visit(n.init) + '}'
|
|
|
|
|
|
def visit_EmptyStatement(self, n):
|
|
return ';'
|
|
|
|
def visit_ParamList(self, n):
|
|
return ', '.join(self.visit(param) for param in n.params)
|
|
|
|
def visit_Return(self, n):
|
|
s = 'return'
|
|
if n.expr: s += ' ' + self.visit(n.expr)
|
|
return s + ';'
|
|
|
|
def visit_Break(self, n):
|
|
return 'break;'
|
|
|
|
def visit_Continue(self, n):
|
|
return 'continue;'
|
|
|
|
def visit_TernaryOp(self, n):
|
|
s = '(' + self._visit_expr(n.cond) + ') ? '
|
|
s += '(' + self._visit_expr(n.iftrue) + ') : '
|
|
s += '(' + self._visit_expr(n.iffalse) + ')'
|
|
return s
|
|
|
|
def visit_If(self, n):
|
|
s = 'if ('
|
|
if n.cond: s += self.visit(n.cond)
|
|
s += ')\n'
|
|
s += self._generate_stmt(n.iftrue, add_indent=True)
|
|
if n.iffalse:
|
|
s += self._make_indent() + 'else\n'
|
|
s += self._generate_stmt(n.iffalse, add_indent=True)
|
|
return s
|
|
|
|
def visit_For(self, n):
|
|
s = 'for ('
|
|
if n.init: s += self.visit(n.init)
|
|
s += ';'
|
|
if n.cond: s += ' ' + self.visit(n.cond)
|
|
s += ';'
|
|
if n.next: s += ' ' + self.visit(n.next)
|
|
s += ')\n'
|
|
s += self._generate_stmt(n.stmt, add_indent=True)
|
|
return s
|
|
|
|
def visit_While(self, n):
|
|
s = 'while ('
|
|
if n.cond: s += self.visit(n.cond)
|
|
s += ')\n'
|
|
s += self._generate_stmt(n.stmt, add_indent=True)
|
|
return s
|
|
|
|
def visit_DoWhile(self, n):
|
|
s = 'do\n'
|
|
s += self._generate_stmt(n.stmt, add_indent=True)
|
|
s += self._make_indent() + 'while ('
|
|
if n.cond: s += self.visit(n.cond)
|
|
s += ');'
|
|
return s
|
|
|
|
def visit_StaticAssert(self, n):
|
|
s = '_Static_assert('
|
|
s += self.visit(n.cond)
|
|
if n.message:
|
|
s += ','
|
|
s += self.visit(n.message)
|
|
s += ')'
|
|
return s
|
|
|
|
def visit_Switch(self, n):
|
|
s = 'switch (' + self.visit(n.cond) + ')\n'
|
|
s += self._generate_stmt(n.stmt, add_indent=True)
|
|
return s
|
|
|
|
def visit_Case(self, n):
|
|
s = 'case ' + self.visit(n.expr) + ':\n'
|
|
for stmt in n.stmts:
|
|
s += self._generate_stmt(stmt, add_indent=True)
|
|
return s
|
|
|
|
def visit_Default(self, n):
|
|
s = 'default:\n'
|
|
for stmt in n.stmts:
|
|
s += self._generate_stmt(stmt, add_indent=True)
|
|
return s
|
|
|
|
def visit_Label(self, n):
|
|
return n.name + ':\n' + self._generate_stmt(n.stmt)
|
|
|
|
def visit_Goto(self, n):
|
|
return 'goto ' + n.name + ';'
|
|
|
|
def visit_EllipsisParam(self, n):
|
|
return '...'
|
|
|
|
def visit_Struct(self, n):
|
|
return self._generate_struct_union_enum(n, 'struct')
|
|
|
|
def visit_Typename(self, n):
|
|
return self._generate_type(n.type)
|
|
|
|
def visit_Union(self, n):
|
|
return self._generate_struct_union_enum(n, 'union')
|
|
|
|
def visit_NamedInitializer(self, n):
|
|
s = ''
|
|
for name in n.name:
|
|
if isinstance(name, c_ast.ID):
|
|
s += '.' + name.name
|
|
else:
|
|
s += '[' + self.visit(name) + ']'
|
|
s += ' = ' + self._visit_expr(n.expr)
|
|
return s
|
|
|
|
def visit_FuncDecl(self, n):
|
|
return self._generate_type(n)
|
|
|
|
def visit_ArrayDecl(self, n):
|
|
return self._generate_type(n, emit_declname=False)
|
|
|
|
def visit_TypeDecl(self, n):
|
|
return self._generate_type(n, emit_declname=False)
|
|
|
|
def visit_PtrDecl(self, n):
|
|
return self._generate_type(n, emit_declname=False)
|
|
|
|
def _generate_struct_union_enum(self, n, name):
|
|
""" Generates code for structs, unions, and enums. name should be
|
|
'struct', 'union', or 'enum'.
|
|
"""
|
|
if name in ('struct', 'union'):
|
|
members = n.decls
|
|
body_function = self._generate_struct_union_body
|
|
else:
|
|
assert name == 'enum'
|
|
members = None if n.values is None else n.values.enumerators
|
|
body_function = self._generate_enum_body
|
|
s = name + ' ' + (n.name or '')
|
|
if members is not None:
|
|
# None means no members
|
|
# Empty sequence means an empty list of members
|
|
s += '\n'
|
|
s += self._make_indent()
|
|
self.indent_level += 2
|
|
s += '{\n'
|
|
s += body_function(members)
|
|
self.indent_level -= 2
|
|
s += self._make_indent() + '}'
|
|
return s
|
|
|
|
def _generate_struct_union_body(self, members):
|
|
return ''.join(self._generate_stmt(decl) for decl in members)
|
|
|
|
def _generate_enum_body(self, members):
|
|
# `[:-2] + '\n'` removes the final `,` from the enumerator list
|
|
return ''.join(self.visit(value) for value in members)[:-2] + '\n'
|
|
|
|
def _generate_stmt(self, n, add_indent=False):
|
|
""" Generation from a statement node. This method exists as a wrapper
|
|
for individual visit_* methods to handle different treatment of
|
|
some statements in this context.
|
|
"""
|
|
typ = type(n)
|
|
if add_indent: self.indent_level += 2
|
|
indent = self._make_indent()
|
|
if add_indent: self.indent_level -= 2
|
|
|
|
if typ in (
|
|
c_ast.Decl, c_ast.Assignment, c_ast.Cast, c_ast.UnaryOp,
|
|
c_ast.BinaryOp, c_ast.TernaryOp, c_ast.FuncCall, c_ast.ArrayRef,
|
|
c_ast.StructRef, c_ast.Constant, c_ast.ID, c_ast.Typedef,
|
|
c_ast.ExprList):
|
|
# These can also appear in an expression context so no semicolon
|
|
# is added to them automatically
|
|
#
|
|
return indent + self.visit(n) + ';\n'
|
|
elif typ in (c_ast.Compound,):
|
|
# No extra indentation required before the opening brace of a
|
|
# compound - because it consists of multiple lines it has to
|
|
# compute its own indentation.
|
|
#
|
|
return self.visit(n)
|
|
elif typ in (c_ast.If,):
|
|
return indent + self.visit(n)
|
|
else:
|
|
return indent + self.visit(n) + '\n'
|
|
|
|
def _generate_decl(self, n):
|
|
""" Generation from a Decl node.
|
|
"""
|
|
s = ''
|
|
if n.funcspec: s = ' '.join(n.funcspec) + ' '
|
|
if n.storage: s += ' '.join(n.storage) + ' '
|
|
if n.align: s += self.visit(n.align[0]) + ' '
|
|
s += self._generate_type(n.type)
|
|
return s
|
|
|
|
def _generate_type(self, n, modifiers=[], emit_declname = True):
|
|
""" Recursive generation from a type node. n is the type node.
|
|
modifiers collects the PtrDecl, ArrayDecl and FuncDecl modifiers
|
|
encountered on the way down to a TypeDecl, to allow proper
|
|
generation from it.
|
|
"""
|
|
typ = type(n)
|
|
#~ print(n, modifiers)
|
|
|
|
if typ == c_ast.TypeDecl:
|
|
s = ''
|
|
if n.quals: s += ' '.join(n.quals) + ' '
|
|
s += self.visit(n.type)
|
|
|
|
nstr = n.declname if n.declname and emit_declname else ''
|
|
# Resolve modifiers.
|
|
# Wrap in parens to distinguish pointer to array and pointer to
|
|
# function syntax.
|
|
#
|
|
for i, modifier in enumerate(modifiers):
|
|
if isinstance(modifier, c_ast.ArrayDecl):
|
|
if (i != 0 and
|
|
isinstance(modifiers[i - 1], c_ast.PtrDecl)):
|
|
nstr = '(' + nstr + ')'
|
|
nstr += '['
|
|
if modifier.dim_quals:
|
|
nstr += ' '.join(modifier.dim_quals) + ' '
|
|
nstr += self.visit(modifier.dim) + ']'
|
|
elif isinstance(modifier, c_ast.FuncDecl):
|
|
if (i != 0 and
|
|
isinstance(modifiers[i - 1], c_ast.PtrDecl)):
|
|
nstr = '(' + nstr + ')'
|
|
nstr += '(' + self.visit(modifier.args) + ')'
|
|
elif isinstance(modifier, c_ast.PtrDecl):
|
|
if modifier.quals:
|
|
nstr = '* %s%s' % (' '.join(modifier.quals),
|
|
' ' + nstr if nstr else '')
|
|
else:
|
|
nstr = '*' + nstr
|
|
if nstr: s += ' ' + nstr
|
|
return s
|
|
elif typ == c_ast.Decl:
|
|
return self._generate_decl(n.type)
|
|
elif typ == c_ast.Typename:
|
|
return self._generate_type(n.type, emit_declname = emit_declname)
|
|
elif typ == c_ast.IdentifierType:
|
|
return ' '.join(n.names) + ' '
|
|
elif typ in (c_ast.ArrayDecl, c_ast.PtrDecl, c_ast.FuncDecl):
|
|
return self._generate_type(n.type, modifiers + [n],
|
|
emit_declname = emit_declname)
|
|
else:
|
|
return self.visit(n)
|
|
|
|
def _parenthesize_if(self, n, condition):
|
|
""" Visits 'n' and returns its string representation, parenthesized
|
|
if the condition function applied to the node returns True.
|
|
"""
|
|
s = self._visit_expr(n)
|
|
if condition(n):
|
|
return '(' + s + ')'
|
|
else:
|
|
return s
|
|
|
|
def _parenthesize_unless_simple(self, n):
|
|
""" Common use case for _parenthesize_if
|
|
"""
|
|
return self._parenthesize_if(n, lambda d: not self._is_simple_node(d))
|
|
|
|
def _is_simple_node(self, n):
|
|
""" Returns True for nodes that are "simple" - i.e. nodes that always
|
|
have higher precedence than operators.
|
|
"""
|
|
return isinstance(n, (c_ast.Constant, c_ast.ID, c_ast.ArrayRef,
|
|
c_ast.StructRef, c_ast.FuncCall))
|