diff options
Diffstat (limited to 'lib/pycparser/c_generator.py')
| -rw-r--r-- | lib/pycparser/c_generator.py | 502 |
1 files changed, 502 insertions, 0 deletions
diff --git a/lib/pycparser/c_generator.py b/lib/pycparser/c_generator.py new file mode 100644 index 0000000..1057b2c --- /dev/null +++ b/lib/pycparser/c_generator.py @@ -0,0 +1,502 @@ +#------------------------------------------------------------------------------ +# 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)) |