Decrease memory usage of pycparser by using __slots__ in AST nodes.

In general, there's no need to dynamically adjust the attributes of AST nodes.
So __slots__ seems suitable.

This reduces the memory usage of the test case reported in issue #72 from 21MB
to 17.5MB and should reduce the amount of space consumed by AST nodes in
general.

5 files changed, 102 insertions, 28 deletions

diff --git a/pycparser/_ast_gen.py b/pycparser/_ast_gen.py
index 307ece5..654fad6 100644
--- a/pycparser/_ast_gen.py
+++ b/pycparser/_ast_gen.py
@@ -92,10 +92,14 @@ class NodeCfg(object):
 
         if self.all_entries:
             args = ', '.join(self.all_entries)
+            slots = ', '.join("'{0}'".format(e) for e in self.all_entries)
+            slots += ", 'coord'"
             arglist = '(self, %s, coord=None)' % args
         else:
+            slots = "'coord',"
             arglist = '(self, coord=None)'
 
+        src += "    __slots__ = (%s)\n" % slots
         src += "    def __init__%s:\n" % arglist
 
         for name in self.all_entries + ['coord']:
@@ -128,7 +132,7 @@ class NodeCfg(object):
         return src
 
     def _gen_attr_names(self):
-        src = "    attr_names = (" + ''.join("%r," % nm for nm in self.attr) + ')'
+        src = "    attr_names = (" + ''.join("%r, " % nm for nm in self.attr) + ')'
         return src
 
 
@@ -157,6 +161,7 @@ import sys
 
 
 class Node(object):
+    __slots__ = ()
     """ Abstract base class for AST nodes.
     """
     def children(self):
diff --git a/pycparser/_c_ast.cfg b/pycparser/_c_ast.cfg
index b9fce05..5323e57 100644
--- a/pycparser/_c_ast.cfg
+++ b/pycparser/_c_ast.cfg
@@ -177,7 +177,7 @@ TypeDecl: [declname, quals, type*]
 #
 Typedef: [name, quals, storage, type*]
 
-Typename: [quals, type*]
+Typename: [name, quals, type*]
 
 UnaryOp: [op, expr*]
 
@@ -187,6 +187,3 @@ UnaryOp: [op, expr*]
 Union: [name, decls**]
 
 While: [cond*, stmt*]
-
-
-
diff --git a/pycparser/c_ast.py b/pycparser/c_ast.py
index 212019a..04a6e5e 100644
--- a/pycparser/c_ast.py
+++ b/pycparser/c_ast.py
@@ -20,6 +20,7 @@ import sys
 
 
 class Node(object):
+    __slots__ = ()
     """ Abstract base class for AST nodes.
     """
     def children(self):
@@ -127,6 +128,7 @@ class NodeVisitor(object):
 
 
 class ArrayDecl(Node):
+    __slots__ = ('type', 'dim', 'dim_quals', 'coord')
     def __init__(self, type, dim, dim_quals, coord=None):
         self.type = type
         self.dim = dim
@@ -139,9 +141,10 @@ class ArrayDecl(Node):
         if self.dim is not None: nodelist.append(("dim", self.dim))
         return tuple(nodelist)
 
-    attr_names = ('dim_quals',)
+    attr_names = ('dim_quals', )
 
 class ArrayRef(Node):
+    __slots__ = ('name', 'subscript', 'coord')
     def __init__(self, name, subscript, coord=None):
         self.name = name
         self.subscript = subscript
@@ -156,6 +159,7 @@ class ArrayRef(Node):
     attr_names = ()
 
 class Assignment(Node):
+    __slots__ = ('op', 'lvalue', 'rvalue', 'coord')
     def __init__(self, op, lvalue, rvalue, coord=None):
         self.op = op
         self.lvalue = lvalue
@@ -168,9 +172,10 @@ class Assignment(Node):
         if self.rvalue is not None: nodelist.append(("rvalue", self.rvalue))
         return tuple(nodelist)
 
-    attr_names = ('op',)
+    attr_names = ('op', )
 
 class BinaryOp(Node):
+    __slots__ = ('op', 'left', 'right', 'coord')
     def __init__(self, op, left, right, coord=None):
         self.op = op
         self.left = left
@@ -183,9 +188,10 @@ class BinaryOp(Node):
         if self.right is not None: nodelist.append(("right", self.right))
         return tuple(nodelist)
 
-    attr_names = ('op',)
+    attr_names = ('op', )
 
 class Break(Node):
+    __slots__ = ('coord',)
     def __init__(self, coord=None):
         self.coord = coord
 
@@ -195,6 +201,7 @@ class Break(Node):
     attr_names = ()
 
 class Case(Node):
+    __slots__ = ('expr', 'stmts', 'coord')
     def __init__(self, expr, stmts, coord=None):
         self.expr = expr
         self.stmts = stmts
@@ -210,6 +217,7 @@ class Case(Node):
     attr_names = ()
 
 class Cast(Node):
+    __slots__ = ('to_type', 'expr', 'coord')
     def __init__(self, to_type, expr, coord=None):
         self.to_type = to_type
         self.expr = expr
@@ -224,6 +232,7 @@ class Cast(Node):
     attr_names = ()
 
 class Compound(Node):
+    __slots__ = ('block_items', 'coord')
     def __init__(self, block_items, coord=None):
         self.block_items = block_items
         self.coord = coord
@@ -237,6 +246,7 @@ class Compound(Node):
     attr_names = ()
 
 class CompoundLiteral(Node):
+    __slots__ = ('type', 'init', 'coord')
     def __init__(self, type, init, coord=None):
         self.type = type
         self.init = init
@@ -251,6 +261,7 @@ class CompoundLiteral(Node):
     attr_names = ()
 
 class Constant(Node):
+    __slots__ = ('type', 'value', 'coord')
     def __init__(self, type, value, coord=None):
         self.type = type
         self.value = value
@@ -260,9 +271,10 @@ class Constant(Node):
         nodelist = []
         return tuple(nodelist)
 
-    attr_names = ('type','value',)
+    attr_names = ('type', 'value', )
 
 class Continue(Node):
+    __slots__ = ('coord',)
     def __init__(self, coord=None):
         self.coord = coord
 
@@ -272,6 +284,7 @@ class Continue(Node):
     attr_names = ()
 
 class Decl(Node):
+    __slots__ = ('name', 'quals', 'storage', 'funcspec', 'type', 'init', 'bitsize', 'coord')
     def __init__(self, name, quals, storage, funcspec, type, init, bitsize, coord=None):
         self.name = name
         self.quals = quals
@@ -289,9 +302,10 @@ class Decl(Node):
         if self.bitsize is not None: nodelist.append(("bitsize", self.bitsize))
         return tuple(nodelist)
 
-    attr_names = ('name','quals','storage','funcspec',)
+    attr_names = ('name', 'quals', 'storage', 'funcspec', )
 
 class DeclList(Node):
+    __slots__ = ('decls', 'coord')
     def __init__(self, decls, coord=None):
         self.decls = decls
         self.coord = coord
@@ -305,6 +319,7 @@ class DeclList(Node):
     attr_names = ()
 
 class Default(Node):
+    __slots__ = ('stmts', 'coord')
     def __init__(self, stmts, coord=None):
         self.stmts = stmts
         self.coord = coord
@@ -318,6 +333,7 @@ class Default(Node):
     attr_names = ()
 
 class DoWhile(Node):
+    __slots__ = ('cond', 'stmt', 'coord')
     def __init__(self, cond, stmt, coord=None):
         self.cond = cond
         self.stmt = stmt
@@ -332,6 +348,7 @@ class DoWhile(Node):
     attr_names = ()
 
 class EllipsisParam(Node):
+    __slots__ = ('coord',)
     def __init__(self, coord=None):
         self.coord = coord
 
@@ -341,6 +358,7 @@ class EllipsisParam(Node):
     attr_names = ()
 
 class EmptyStatement(Node):
+    __slots__ = ('coord',)
     def __init__(self, coord=None):
         self.coord = coord
 
@@ -350,6 +368,7 @@ class EmptyStatement(Node):
     attr_names = ()
 
 class Enum(Node):
+    __slots__ = ('name', 'values', 'coord')
     def __init__(self, name, values, coord=None):
         self.name = name
         self.values = values
@@ -360,9 +379,10 @@ class Enum(Node):
         if self.values is not None: nodelist.append(("values", self.values))
         return tuple(nodelist)
 
-    attr_names = ('name',)
+    attr_names = ('name', )
 
 class Enumerator(Node):
+    __slots__ = ('name', 'value', 'coord')
     def __init__(self, name, value, coord=None):
         self.name = name
         self.value = value
@@ -373,9 +393,10 @@ class Enumerator(Node):
         if self.value is not None: nodelist.append(("value", self.value))
         return tuple(nodelist)
 
-    attr_names = ('name',)
+    attr_names = ('name', )
 
 class EnumeratorList(Node):
+    __slots__ = ('enumerators', 'coord')
     def __init__(self, enumerators, coord=None):
         self.enumerators = enumerators
         self.coord = coord
@@ -389,6 +410,7 @@ class EnumeratorList(Node):
     attr_names = ()
 
 class ExprList(Node):
+    __slots__ = ('exprs', 'coord')
     def __init__(self, exprs, coord=None):
         self.exprs = exprs
         self.coord = coord
@@ -402,6 +424,7 @@ class ExprList(Node):
     attr_names = ()
 
 class FileAST(Node):
+    __slots__ = ('ext', 'coord')
     def __init__(self, ext, coord=None):
         self.ext = ext
         self.coord = coord
@@ -415,6 +438,7 @@ class FileAST(Node):
     attr_names = ()
 
 class For(Node):
+    __slots__ = ('init', 'cond', 'next', 'stmt', 'coord')
     def __init__(self, init, cond, next, stmt, coord=None):
         self.init = init
         self.cond = cond
@@ -433,6 +457,7 @@ class For(Node):
     attr_names = ()
 
 class FuncCall(Node):
+    __slots__ = ('name', 'args', 'coord')
     def __init__(self, name, args, coord=None):
         self.name = name
         self.args = args
@@ -447,6 +472,7 @@ class FuncCall(Node):
     attr_names = ()
 
 class FuncDecl(Node):
+    __slots__ = ('args', 'type', 'coord')
     def __init__(self, args, type, coord=None):
         self.args = args
         self.type = type
@@ -461,6 +487,7 @@ class FuncDecl(Node):
     attr_names = ()
 
 class FuncDef(Node):
+    __slots__ = ('decl', 'param_decls', 'body', 'coord')
     def __init__(self, decl, param_decls, body, coord=None):
         self.decl = decl
         self.param_decls = param_decls
@@ -478,6 +505,7 @@ class FuncDef(Node):
     attr_names = ()
 
 class Goto(Node):
+    __slots__ = ('name', 'coord')
     def __init__(self, name, coord=None):
         self.name = name
         self.coord = coord
@@ -486,9 +514,10 @@ class Goto(Node):
         nodelist = []
         return tuple(nodelist)
 
-    attr_names = ('name',)
+    attr_names = ('name', )
 
 class ID(Node):
+    __slots__ = ('name', 'coord')
     def __init__(self, name, coord=None):
         self.name = name
         self.coord = coord
@@ -497,9 +526,10 @@ class ID(Node):
         nodelist = []
         return tuple(nodelist)
 
-    attr_names = ('name',)
+    attr_names = ('name', )
 
 class IdentifierType(Node):
+    __slots__ = ('names', 'coord')
     def __init__(self, names, coord=None):
         self.names = names
         self.coord = coord
@@ -508,9 +538,10 @@ class IdentifierType(Node):
         nodelist = []
         return tuple(nodelist)
 
-    attr_names = ('names',)
+    attr_names = ('names', )
 
 class If(Node):
+    __slots__ = ('cond', 'iftrue', 'iffalse', 'coord')
     def __init__(self, cond, iftrue, iffalse, coord=None):
         self.cond = cond
         self.iftrue = iftrue
@@ -527,6 +558,7 @@ class If(Node):
     attr_names = ()
 
 class InitList(Node):
+    __slots__ = ('exprs', 'coord')
     def __init__(self, exprs, coord=None):
         self.exprs = exprs
         self.coord = coord
@@ -540,6 +572,7 @@ class InitList(Node):
     attr_names = ()
 
 class Label(Node):
+    __slots__ = ('name', 'stmt', 'coord')
     def __init__(self, name, stmt, coord=None):
         self.name = name
         self.stmt = stmt
@@ -550,9 +583,10 @@ class Label(Node):
         if self.stmt is not None: nodelist.append(("stmt", self.stmt))
         return tuple(nodelist)
 
-    attr_names = ('name',)
+    attr_names = ('name', )
 
 class NamedInitializer(Node):
+    __slots__ = ('name', 'expr', 'coord')
     def __init__(self, name, expr, coord=None):
         self.name = name
         self.expr = expr
@@ -568,6 +602,7 @@ class NamedInitializer(Node):
     attr_names = ()
 
 class ParamList(Node):
+    __slots__ = ('params', 'coord')
     def __init__(self, params, coord=None):
         self.params = params
         self.coord = coord
@@ -581,6 +616,7 @@ class ParamList(Node):
     attr_names = ()
 
 class PtrDecl(Node):
+    __slots__ = ('quals', 'type', 'coord')
     def __init__(self, quals, type, coord=None):
         self.quals = quals
         self.type = type
@@ -591,9 +627,10 @@ class PtrDecl(Node):
         if self.type is not None: nodelist.append(("type", self.type))
         return tuple(nodelist)
 
-    attr_names = ('quals',)
+    attr_names = ('quals', )
 
 class Return(Node):
+    __slots__ = ('expr', 'coord')
     def __init__(self, expr, coord=None):
         self.expr = expr
         self.coord = coord
@@ -606,6 +643,7 @@ class Return(Node):
     attr_names = ()
 
 class Struct(Node):
+    __slots__ = ('name', 'decls', 'coord')
     def __init__(self, name, decls, coord=None):
         self.name = name
         self.decls = decls
@@ -617,9 +655,10 @@ class Struct(Node):
             nodelist.append(("decls[%d]" % i, child))
         return tuple(nodelist)
 
-    attr_names = ('name',)
+    attr_names = ('name', )
 
 class StructRef(Node):
+    __slots__ = ('name', 'type', 'field', 'coord')
     def __init__(self, name, type, field, coord=None):
         self.name = name
         self.type = type
@@ -632,9 +671,10 @@ class StructRef(Node):
         if self.field is not None: nodelist.append(("field", self.field))
         return tuple(nodelist)
 
-    attr_names = ('type',)
+    attr_names = ('type', )
 
 class Switch(Node):
+    __slots__ = ('cond', 'stmt', 'coord')
     def __init__(self, cond, stmt, coord=None):
         self.cond = cond
         self.stmt = stmt
@@ -649,6 +689,7 @@ class Switch(Node):
     attr_names = ()
 
 class TernaryOp(Node):
+    __slots__ = ('cond', 'iftrue', 'iffalse', 'coord')
     def __init__(self, cond, iftrue, iffalse, coord=None):
         self.cond = cond
         self.iftrue = iftrue
@@ -665,6 +706,7 @@ class TernaryOp(Node):
     attr_names = ()
 
 class TypeDecl(Node):
+    __slots__ = ('declname', 'quals', 'type', 'coord')
     def __init__(self, declname, quals, type, coord=None):
         self.declname = declname
         self.quals = quals
@@ -676,9 +718,10 @@ class TypeDecl(Node):
         if self.type is not None: nodelist.append(("type", self.type))
         return tuple(nodelist)
 
-    attr_names = ('declname','quals',)
+    attr_names = ('declname', 'quals', )
 
 class Typedef(Node):
+    __slots__ = ('name', 'quals', 'storage', 'type', 'coord')
     def __init__(self, name, quals, storage, type, coord=None):
         self.name = name
         self.quals = quals
@@ -691,10 +734,12 @@ class Typedef(Node):
         if self.type is not None: nodelist.append(("type", self.type))
         return tuple(nodelist)
 
-    attr_names = ('name','quals','storage',)
+    attr_names = ('name', 'quals', 'storage', )
 
 class Typename(Node):
-    def __init__(self, quals, type, coord=None):
+    __slots__ = ('name', 'quals', 'type', 'coord')
+    def __init__(self, name, quals, type, coord=None):
+        self.name = name
         self.quals = quals
         self.type = type
         self.coord = coord
@@ -704,9 +749,10 @@ class Typename(Node):
         if self.type is not None: nodelist.append(("type", self.type))
         return tuple(nodelist)
 
-    attr_names = ('quals',)
+    attr_names = ('name', 'quals', )
 
 class UnaryOp(Node):
+    __slots__ = ('op', 'expr', 'coord')
     def __init__(self, op, expr, coord=None):
         self.op = op
         self.expr = expr
@@ -717,9 +763,10 @@ class UnaryOp(Node):
         if self.expr is not None: nodelist.append(("expr", self.expr))
         return tuple(nodelist)
 
-    attr_names = ('op',)
+    attr_names = ('op', )
 
 class Union(Node):
+    __slots__ = ('name', 'decls', 'coord')
     def __init__(self, name, decls, coord=None):
         self.name = name
         self.decls = decls
@@ -731,9 +778,10 @@ class Union(Node):
             nodelist.append(("decls[%d]" % i, child))
         return tuple(nodelist)
 
-    attr_names = ('name',)
+    attr_names = ('name', )
 
 class While(Node):
+    __slots__ = ('cond', 'stmt', 'coord')
     def __init__(self, cond, stmt, coord=None):
         self.cond = cond
         self.stmt = stmt
diff --git a/pycparser/c_parser.py b/pycparser/c_parser.py
index 643b88c..4eb26b6 100644
--- a/pycparser/c_parser.py
+++ b/pycparser/c_parser.py
@@ -1124,6 +1124,7 @@ class CParser(PLYParser):
         #
         else:
             decl = c_ast.Typename(
+                name='',
                 quals=spec['qual'],
                 type=p[2] or c_ast.TypeDecl(None, None, None),
                 coord=self._coord(p.lineno(2)))
@@ -1195,6 +1196,7 @@ class CParser(PLYParser):
         #~ print '=========='
 
         typename = c_ast.Typename(
+            name='',
             quals=p[1]['qual'],
             type=p[2] or c_ast.TypeDecl(None, None, None),
             coord=self._coord(p.lineno(2)))
diff --git a/z.py b/z.py
index 9031e03..d881240 100644
--- a/z.py
+++ b/z.py
@@ -1,4 +1,5 @@
 import sys
+from pycparser import parse_file
 from pycparser.c_ast import *
 from pycparser.c_parser import CParser, Coord, ParseError
 from pycparser.c_lexer import CLexer
@@ -74,12 +75,33 @@ class NodeVisitor(object):
         self.current_parent = oldparent
 
 
+def memprofile():
+    import resource
+    import tracemalloc
+
+    tracemalloc.start()
+
+    ast = parse_file('/tmp/197.c')
+
+    print('Memory usage: %s (kb)' %
+            resource.getrusage(resource.RUSAGE_SELF).ru_maxrss)
+
+    snapshot = tracemalloc.take_snapshot()
+    print("[ tracemalloc stats ]")
+    for stat in snapshot.statistics('lineno')[:20]:
+        print(stat)
+
+
 if __name__ == "__main__":
     source_code = r'''void foo() {
     L"hi" L"there";
 }
     '''
 
-    parser = CParser()
-    ast = parser.parse(source_code, filename='zz')
-    ast.show(showcoord=True, attrnames=True, nodenames=True)
+    memprofile()
+
+    #parser = CParser()
+    #ast = parser.parse(source_code, filename='zz')
+    #ast.show(showcoord=True, attrnames=True, nodenames=True)
+
+