cpython/Lib/compiler/pycodegen.py

import os
import marshal
import stat
import string
import struct
import types
from cStringIO import StringIO

from compiler import ast, parse, walk
from compiler import pyassem, misc
from compiler.pyassem import CO_VARARGS, CO_VARKEYWORDS, CO_NEWLOCALS, TupleArg

callfunc_opcode_info = {
    # (Have *args, Have **args) : opcode
    (0,0) : "CALL_FUNCTION",
    (1,0) : "CALL_FUNCTION_VAR",
    (0,1) : "CALL_FUNCTION_KW",
    (1,1) : "CALL_FUNCTION_VAR_KW",
}

def compile(filename):
    f = open(filename)
    buf = f.read()
    f.close()
    mod = Module(buf, filename)
    mod.compile()
    f = open(filename + "c", "wb")
    mod.dump(f)
    f.close()

class Module:
    def __init__(self, source, filename):
        self.filename = filename
        self.source = source
        self.code = None

    def compile(self):
        ast = parse(self.source)
        root, filename = os.path.split(self.filename)
        gen = ModuleCodeGenerator(filename)
        walk(ast, gen, 1)
        self.code = gen.getCode()

    def dump(self, f):
        f.write(self.getPycHeader())
        marshal.dump(self.code, f)

    MAGIC = (50823 | (ord('\r')<<16) | (ord('\n')<<24))

    def getPycHeader(self):
        # compile.c uses marshal to write a long directly, with
        # calling the interface that would also generate a 1-byte code
        # to indicate the type of the value.  simplest way to get the
        # same effect is to call marshal and then skip the code.
        magic = marshal.dumps(self.MAGIC)[1:]
        mtime = os.stat(self.filename)[stat.ST_MTIME]
        mtime = struct.pack('i', mtime)
        return magic + mtime

class CodeGenerator:

    optimized = 0 # is namespace access optimized?

    def __init__(self, filename):
## Subclasses must define a constructor that intializes self.graph
## before calling this init function
##         self.graph = pyassem.PyFlowGraph()
        self.filename = filename
        self.locals = misc.Stack()
        self.loops = misc.Stack()
        self.curStack = 0
        self.maxStack = 0
        self.last_lineno = None
        self._setupGraphDelegation()

    def _setupGraphDelegation(self):
        self.emit = self.graph.emit
        self.newBlock = self.graph.newBlock
        self.startBlock = self.graph.startBlock
        self.nextBlock = self.graph.nextBlock
        self.setDocstring = self.graph.setDocstring

    def getCode(self):
        """Return a code object"""
        return self.graph.getCode()

    # Next five methods handle name access

    def isLocalName(self, name):
        return self.locals.top().has_elt(name)

    def storeName(self, name):
        self._nameOp('STORE', name)

    def loadName(self, name):
        self._nameOp('LOAD', name)

    def delName(self, name):
        self._nameOp('DELETE', name)

    def _nameOp(self, prefix, name):
        if not self.optimized:
            self.emit(prefix + '_NAME', name)
            return
        if self.isLocalName(name):
            self.emit(prefix + '_FAST', name)
        else:
            self.emit(prefix + '_GLOBAL', name)

    def set_lineno(self, node):
        """Emit SET_LINENO if node has lineno attribute and it is 
        different than the last lineno emitted.

        Returns true if SET_LINENO was emitted.

        There are no rules for when an AST node should have a lineno
        attribute.  The transformer and AST code need to be reviewed
        and a consistent policy implemented and documented.  Until
        then, this method works around missing line numbers.
        """
        lineno = getattr(node, 'lineno', None)
        if lineno is not None and lineno != self.last_lineno:
            self.emit('SET_LINENO', lineno)
            self.last_lineno = lineno
            return 1
        return 0

    # The first few visitor methods handle nodes that generator new
    # code objects 

    def visitModule(self, node):
        lnf = walk(node.node, LocalNameFinder(), 0)
        self.locals.push(lnf.getLocals())
        self.setDocstring(node.doc)
        self.visit(node.node)
        self.emit('LOAD_CONST', None)
        self.emit('RETURN_VALUE')

    def visitFunction(self, node):
        self._visitFuncOrLambda(node, isLambda=0)
        self.storeName(node.name)

    def visitLambda(self, node):
        self._visitFuncOrLambda(node, isLambda=1)
##        self.storeName("<lambda>")

    def _visitFuncOrLambda(self, node, isLambda):
        gen = FunctionCodeGenerator(node, self.filename, isLambda)
        walk(node.code, gen)
        gen.finish()
        self.set_lineno(node)
        for default in node.defaults:
            self.visit(default)
        self.emit('LOAD_CONST', gen.getCode())
        self.emit('MAKE_FUNCTION', len(node.defaults))

    def visitClass(self, node):
        gen = ClassCodeGenerator(node, self.filename)
        walk(node.code, gen)
        gen.finish()
        self.set_lineno(node)
        self.emit('LOAD_CONST', node.name)
        for base in node.bases:
            self.visit(base)
        self.emit('BUILD_TUPLE', len(node.bases))
        self.emit('LOAD_CONST', gen.getCode())
        self.emit('MAKE_FUNCTION', 0)
        self.emit('CALL_FUNCTION', 0)
        self.emit('BUILD_CLASS')
        self.storeName(node.name)

    # The rest are standard visitor methods

    # The next few implement control-flow statements

    def visitIf(self, node):
        end = self.newBlock()
        numtests = len(node.tests)
        for i in range(numtests):
            test, suite = node.tests[i]
            self.set_lineno(test)
            self.visit(test)
##            if i == numtests - 1 and not node.else_:
##                nextTest = end
##            else:
##                nextTest = self.newBlock()
            nextTest = self.newBlock()
            self.emit('JUMP_IF_FALSE', nextTest)
            self.nextBlock()
            self.emit('POP_TOP')
            self.visit(suite)
            self.emit('JUMP_FORWARD', end)
            self.nextBlock(nextTest)
            self.emit('POP_TOP')
        if node.else_:
            self.visit(node.else_)
        self.nextBlock(end)

    def visitWhile(self, node):
        self.set_lineno(node)

        loop = self.newBlock()
        else_ = self.newBlock()

        after = self.newBlock()
        self.emit('SETUP_LOOP', after)

        self.nextBlock(loop)
        self.loops.push(loop)

        self.set_lineno(node)
        self.visit(node.test)
        self.emit('JUMP_IF_FALSE', else_ or after)

        self.nextBlock()
        self.emit('POP_TOP')
        self.visit(node.body)
        self.emit('JUMP_ABSOLUTE', loop)

        self.startBlock(else_) # or just the POPs if not else clause
        self.emit('POP_TOP')
        self.emit('POP_BLOCK')
        if node.else_:
            self.visit(node.else_)
        self.loops.pop()
        self.nextBlock(after)

    def visitFor(self, node):
        start = self.newBlock()
        anchor = self.newBlock()
        after = self.newBlock()
        self.loops.push(start)

        self.set_lineno(node)
        self.emit('SETUP_LOOP', after)
        self.visit(node.list)
        self.visit(ast.Const(0))
        self.nextBlock(start)
        self.set_lineno(node)
        self.emit('FOR_LOOP', anchor)
        self.visit(node.assign)
        self.visit(node.body)
        self.emit('JUMP_ABSOLUTE', start)
        self.nextBlock(anchor)
        self.emit('POP_BLOCK')
        if node.else_:
            self.visit(node.else_)
        self.loops.pop()
        self.nextBlock(after)

    def visitBreak(self, node):
        if not self.loops:
            raise SyntaxError, "'break' outside loop (%s, %d)" % \
                  (self.filename, node.lineno)
        self.set_lineno(node)
        self.emit('BREAK_LOOP')

    def visitContinue(self, node):
        if not self.loops:
            raise SyntaxError, "'continue' outside loop (%s, %d)" % \
                  (self.filename, node.lineno)
        l = self.loops.top()
        self.set_lineno(node)
        self.emit('JUMP_ABSOLUTE', l)
        self.nextBlock()

    def visitTest(self, node, jump):
        end = self.newBlock()
        for child in node.nodes[:-1]:
            self.visit(child)
            self.emit(jump, end)
            self.nextBlock()
            self.emit('POP_TOP')
        self.visit(node.nodes[-1])
        self.nextBlock(end)

    def visitAnd(self, node):
        self.visitTest(node, 'JUMP_IF_FALSE')

    def visitOr(self, node):
        self.visitTest(node, 'JUMP_IF_TRUE')

    def visitCompare(self, node):
        self.visit(node.expr)
        cleanup = self.newBlock()
        for op, code in node.ops[:-1]:
            self.visit(code)
            self.emit('DUP_TOP')
            self.emit('ROT_THREE')
            self.emit('COMPARE_OP', op)
            self.emit('JUMP_IF_FALSE', cleanup)
            self.nextBlock()
            self.emit('POP_TOP')
        # now do the last comparison
        if node.ops:
            op, code = node.ops[-1]
            self.visit(code)
            self.emit('COMPARE_OP', op)
        if len(node.ops) > 1:
            end = self.newBlock()
            self.emit('JUMP_FORWARD', end)
            self.nextBlock(cleanup)
            self.emit('ROT_TWO')
            self.emit('POP_TOP')
            self.nextBlock(end)

    # exception related

    def visitAssert(self, node):
        # XXX would be interesting to implement this via a
        # transformation of the AST before this stage
        end = self.newBlock()
        self.set_lineno(node)
        # XXX __debug__ and AssertionError appear to be special cases
        # -- they are always loaded as globals even if there are local
        # names.  I guess this is a sort of renaming op.
        self.emit('LOAD_GLOBAL', '__debug__')
        self.emit('JUMP_IF_FALSE', end)
        self.nextBlock()
        self.emit('POP_TOP')
        self.visit(node.test)
        self.emit('JUMP_IF_TRUE', end)
        self.nextBlock()
        self.emit('LOAD_GLOBAL', 'AssertionError')
        self.visit(node.fail)
        self.emit('RAISE_VARARGS', 2)
        self.nextBlock(end)
        self.emit('POP_TOP')

    def visitRaise(self, node):
        self.set_lineno(node)
        n = 0
        if node.expr1:
            self.visit(node.expr1)
            n = n + 1
        if node.expr2:
            self.visit(node.expr2)
            n = n + 1
        if node.expr3:
            self.visit(node.expr3)
            n = n + 1
        self.emit('RAISE_VARARGS', n)

    def visitTryExcept(self, node):
        handlers = self.newBlock()
        end = self.newBlock()
        if node.else_:
            lElse = self.newBlock()
        else:
            lElse = end
        self.set_lineno(node)
        self.emit('SETUP_EXCEPT', handlers)
        self.visit(node.body)
        self.emit('POP_BLOCK')
        self.emit('JUMP_FORWARD', lElse)
        self.nextBlock(handlers)
        
        last = len(node.handlers) - 1
        for i in range(len(node.handlers)):
            expr, target, body = node.handlers[i]
            self.set_lineno(expr)
            if expr:
                self.emit('DUP_TOP')
                self.visit(expr)
                self.emit('COMPARE_OP', 'exception match')
                next = self.newBlock()
                self.emit('JUMP_IF_FALSE', next)
                self.nextBlock()
                self.emit('POP_TOP')
            self.emit('POP_TOP')
            if target:
                self.visit(target)
            else:
                self.emit('POP_TOP')
            self.emit('POP_TOP')
            self.visit(body)
            self.emit('JUMP_FORWARD', end)
            if expr:
                self.nextBlock(next)
            self.emit('POP_TOP')
        self.emit('END_FINALLY')
        if node.else_:
            self.nextBlock(lElse)
            self.visit(node.else_)
        self.nextBlock(end)
    
    def visitTryFinally(self, node):
        final = self.newBlock()
        self.set_lineno(node)
        self.emit('SETUP_FINALLY', final)
        self.visit(node.body)
        self.emit('POP_BLOCK')
        self.emit('LOAD_CONST', None)
        self.nextBlock(final)
        self.visit(node.final)
        self.emit('END_FINALLY')

    # misc

##     def visitStmt(self, node):
##         # nothing to do except walk the children
##         pass

    def visitDiscard(self, node):
        self.visit(node.expr)
        self.emit('POP_TOP')

    def visitConst(self, node):
        self.emit('LOAD_CONST', node.value)

    def visitKeyword(self, node):
        self.emit('LOAD_CONST', node.name)
        self.visit(node.expr)

    def visitGlobal(self, node):
        # no code to generate
        pass

    def visitName(self, node):
        self.set_lineno(node)
        self.loadName(node.name)
        
    def visitPass(self, node):
        self.set_lineno(node)

    def visitImport(self, node):
        self.set_lineno(node)
        for name, alias in node.names:
            self.emit('LOAD_CONST', None)
            self.emit('IMPORT_NAME', name)
            self._resolveDots(name)
            self.storeName(alias or name)

    def visitFrom(self, node):
        self.set_lineno(node)
        fromlist = map(lambda (name, alias): name, node.names)
        self.emit('LOAD_CONST', tuple(fromlist))
        self.emit('IMPORT_NAME', node.modname)
        for name, alias in node.names:
            if name == '*':
                self.namespace = 0
            self.emit('IMPORT_FROM', name)
            self._resolveDots(name)
            self.storeName(alias or name)
        self.emit('POP_TOP')

    def _resolveDots(self, name):
        elts = string.split(name, ".")
        if len(elts) == 1:
            return
        for elt in elts[1:]:
            self.emit('LOAD_ATTR', elt)

    def visitGetattr(self, node):
        self.visit(node.expr)
        self.emit('LOAD_ATTR', node.attrname)

    # next five implement assignments

    def visitAssign(self, node):
        self.set_lineno(node)
        self.visit(node.expr)
        dups = len(node.nodes) - 1
        for i in range(len(node.nodes)):
            elt = node.nodes[i]
            if i < dups:
                self.emit('DUP_TOP')
            if isinstance(elt, ast.Node):
                self.visit(elt)

    def visitAssName(self, node):
        if node.flags == 'OP_ASSIGN':
            self.storeName(node.name)
        elif node.flags == 'OP_DELETE':
            self.delName(node.name)
        else:
            print "oops", node.flags

    def visitAssAttr(self, node):
        self.visit(node.expr)
        if node.flags == 'OP_ASSIGN':
            self.emit('STORE_ATTR', node.attrname)
        elif node.flags == 'OP_DELETE':
            self.emit('DELETE_ATTR', node.attrname)
        else:
            print "warning: unexpected flags:", node.flags
            print node

    def visitAssTuple(self, node):
        if findOp(node) != 'OP_DELETE':
            self.emit('UNPACK_SEQUENCE', len(node.nodes))
        for child in node.nodes:
            self.visit(child)

    visitAssList = visitAssTuple

    def visitExec(self, node):
        self.visit(node.expr)
        if node.locals is None:
            self.emit('LOAD_CONST', None)
        else:
            self.visit(node.locals)
        if node.globals is None:
            self.emit('DUP_TOP')
        else:
            self.visit(node.globals)
        self.emit('EXEC_STMT')

    def visitCallFunc(self, node):
        pos = 0
        kw = 0
        self.set_lineno(node)
        self.visit(node.node)
        for arg in node.args:
            self.visit(arg)
            if isinstance(arg, ast.Keyword):
                kw = kw + 1
            else:
                pos = pos + 1
        if node.star_args is not None:
            self.visit(node.star_args)
        if node.dstar_args is not None:
            self.visit(node.dstar_args)
        have_star = node.star_args is not None
        have_dstar = node.dstar_args is not None
        opcode = callfunc_opcode_info[have_star, have_dstar]
        self.emit(opcode, kw << 8 | pos)

    def visitPrint(self, node):
        self.set_lineno(node)
        for child in node.nodes:
            self.visit(child)
            self.emit('PRINT_ITEM')

    def visitPrintnl(self, node):
        self.visitPrint(node)
        self.emit('PRINT_NEWLINE')

    def visitReturn(self, node):
        self.set_lineno(node)
        self.visit(node.value)
        self.emit('RETURN_VALUE')

    # slice and subscript stuff

    def visitSlice(self, node):
        self.visit(node.expr)
        slice = 0
        if node.lower:
            self.visit(node.lower)
            slice = slice | 1
        if node.upper:
            self.visit(node.upper)
            slice = slice | 2
        if node.flags == 'OP_APPLY':
            self.emit('SLICE+%d' % slice)
        elif node.flags == 'OP_ASSIGN':
            self.emit('STORE_SLICE+%d' % slice)
        elif node.flags == 'OP_DELETE':
            self.emit('DELETE_SLICE+%d' % slice)
        else:
            print "weird slice", node.flags
            raise

    def visitSubscript(self, node):
        self.visit(node.expr)
        for sub in node.subs:
            self.visit(sub)
        if len(node.subs) > 1:
            self.emit('BUILD_TUPLE', len(node.subs))
        if node.flags == 'OP_APPLY':
            self.emit('BINARY_SUBSCR')
        elif node.flags == 'OP_ASSIGN':
            self.emit('STORE_SUBSCR')
        elif node.flags == 'OP_DELETE':
            self.emit('DELETE_SUBSCR')

    # binary ops

    def binaryOp(self, node, op):
        self.visit(node.left)
        self.visit(node.right)
        self.emit(op)

    def visitAdd(self, node):
        return self.binaryOp(node, 'BINARY_ADD')

    def visitSub(self, node):
        return self.binaryOp(node, 'BINARY_SUBTRACT')

    def visitMul(self, node):
        return self.binaryOp(node, 'BINARY_MULTIPLY')

    def visitDiv(self, node):
        return self.binaryOp(node, 'BINARY_DIVIDE')

    def visitMod(self, node):
        return self.binaryOp(node, 'BINARY_MODULO')

    def visitPower(self, node):
        return self.binaryOp(node, 'BINARY_POWER')

    def visitLeftShift(self, node):
        return self.binaryOp(node, 'BINARY_LSHIFT')

    def visitRightShift(self, node):
        return self.binaryOp(node, 'BINARY_RSHIFT')

    # unary ops

    def unaryOp(self, node, op):
        self.visit(node.expr)
        self.emit(op)

    def visitInvert(self, node):
        return self.unaryOp(node, 'UNARY_INVERT')

    def visitUnarySub(self, node):
        return self.unaryOp(node, 'UNARY_NEGATIVE')

    def visitUnaryAdd(self, node):
        return self.unaryOp(node, 'UNARY_POSITIVE')

    def visitUnaryInvert(self, node):
        return self.unaryOp(node, 'UNARY_INVERT')

    def visitNot(self, node):
        return self.unaryOp(node, 'UNARY_NOT')

    def visitBackquote(self, node):
        return self.unaryOp(node, 'UNARY_CONVERT')

    # bit ops

    def bitOp(self, nodes, op):
        self.visit(nodes[0])
        for node in nodes[1:]:
            self.visit(node)
            self.emit(op)

    def visitBitand(self, node):
        return self.bitOp(node.nodes, 'BINARY_AND')

    def visitBitor(self, node):
        return self.bitOp(node.nodes, 'BINARY_OR')

    def visitBitxor(self, node):
        return self.bitOp(node.nodes, 'BINARY_XOR')

    # object constructors

    def visitEllipsis(self, node):
        self.emit('LOAD_CONST', Ellipsis)

    def visitTuple(self, node):
        for elt in node.nodes:
            self.visit(elt)
        self.emit('BUILD_TUPLE', len(node.nodes))

    def visitList(self, node):
        for elt in node.nodes:
            self.visit(elt)
        self.emit('BUILD_LIST', len(node.nodes))

    def visitSliceobj(self, node):
        for child in node.nodes:
            self.visit(child)
        self.emit('BUILD_SLICE', len(node.nodes))

    def visitDict(self, node):
        lineno = getattr(node, 'lineno', None)
        if lineno:
            set.emit('SET_LINENO', lineno)
        self.emit('BUILD_MAP', 0)
        for k, v in node.items:
            lineno2 = getattr(node, 'lineno', None)
            if lineno2 is not None and lineno != lineno2:
                self.emit('SET_LINENO', lineno2)
                lineno = lineno2
            self.emit('DUP_TOP')
            self.visit(v)
            self.emit('ROT_TWO')
            self.visit(k)
            self.emit('STORE_SUBSCR')

class ModuleCodeGenerator(CodeGenerator):
    super_init = CodeGenerator.__init__
    
    def __init__(self, filename):
        # XXX <module> is ? in compile.c
        self.graph = pyassem.PyFlowGraph("<module>", filename)
        self.super_init(filename)

class FunctionCodeGenerator(CodeGenerator):
    super_init = CodeGenerator.__init__

    optimized = 1
    lambdaCount = 0

    def __init__(self, func, filename, isLambda=0):
        if isLambda:
            klass = FunctionCodeGenerator
            name = "<lambda.%d>" % klass.lambdaCount
            klass.lambdaCount = klass.lambdaCount + 1
        else:
            name = func.name
        args, hasTupleArg = generateArgList(func.argnames)
        self.graph = pyassem.PyFlowGraph(name, filename, args, 
                                           optimized=1) 
        self.isLambda = isLambda
        self.super_init(filename)

        lnf = walk(func.code, LocalNameFinder(args), 0)
        self.locals.push(lnf.getLocals())
        if func.varargs:
            self.graph.setFlag(CO_VARARGS)
        if func.kwargs:
            self.graph.setFlag(CO_VARKEYWORDS)
        self.set_lineno(func)
        if hasTupleArg:
            self.generateArgUnpack(func.argnames)

    def finish(self):
        self.graph.startExitBlock()
        if not self.isLambda:
            self.emit('LOAD_CONST', None)
        self.emit('RETURN_VALUE')

    def generateArgUnpack(self, args):
        count = 0
        for arg in args:
            if type(arg) == types.TupleType:
                self.emit('LOAD_FAST', '.nested%d' % count)
                count = count + 1
                self.unpackSequence(arg)
                        
    def unpackSequence(self, tup):
        self.emit('UNPACK_SEQUENCE', len(tup))
        for elt in tup:
            if type(elt) == types.TupleType:
                self.unpackSequence(elt)
            else:
                self.emit('STORE_FAST', elt)

    unpackTuple = unpackSequence

class ClassCodeGenerator(CodeGenerator):
    super_init = CodeGenerator.__init__

    def __init__(self, klass, filename):
        self.graph = pyassem.PyFlowGraph(klass.name, filename,
                                           optimized=0)
        self.super_init(filename)
        lnf = walk(klass.code, LocalNameFinder(), 0)
        self.locals.push(lnf.getLocals())
        self.graph.setFlag(CO_NEWLOCALS)

    def finish(self):
        self.graph.startExitBlock()
        self.emit('LOAD_LOCALS')
        self.emit('RETURN_VALUE')


def generateArgList(arglist):
    """Generate an arg list marking TupleArgs"""
    args = []
    extra = []
    count = 0
    for elt in arglist:
        if type(elt) == types.StringType:
            args.append(elt)
        elif type(elt) == types.TupleType:
            args.append(TupleArg(count, elt))
            count = count + 1
            extra.extend(misc.flatten(elt))
        else:
            raise ValueError, "unexpect argument type:", elt
    return args + extra, count

class LocalNameFinder:
    """Find local names in scope"""
    def __init__(self, names=()):
        self.names = misc.Set()
        self.globals = misc.Set()
        for name in names:
            self.names.add(name)

    def getLocals(self):
        for elt in self.globals.elements():
            if self.names.has_elt(elt):
                self.names.remove(elt)
        return self.names

    def visitDict(self, node):
        pass

    def visitGlobal(self, node):
        for name in node.names:
            self.globals.add(name)

    def visitFunction(self, node):
        self.names.add(node.name)

    def visitLambda(self, node):
        pass

    def visitImport(self, node):
        for name, alias in node.names:
            self.names.add(alias or name)

    def visitFrom(self, node):
        for name, alias in node.names:
            self.names.add(alias or name)

    def visitClass(self, node):
        self.names.add(node.name)

    def visitAssName(self, node):
        self.names.add(node.name)

def findOp(node):
    """Find the op (DELETE, LOAD, STORE) in an AssTuple tree"""
    v = OpFinder()
    walk(node, v, 0)
    return v.op

class OpFinder:
    def __init__(self):
        self.op = None
    def visitAssName(self, node):
        if self.op is None:
            self.op = node.flags
        elif self.op != node.flags:
            raise ValueError, "mixed ops in stmt"

if __name__ == "__main__":
    import sys

    for file in sys.argv[1:]:
        compile(file)