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code.py
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code.py
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from const import *
from symbol import SymbolTable
UNDEF_VALUE = None
def GenExps(ast, symbol, generator):
assert type(ast) == list
for exp in ast:
GenExp(exp, symbol, generator)
generator.gen((OpPop, 1))
def GenExp(ast, symbol, generator, isTail=False):
if not isinstance(ast, list):
SinglarExp(ast, symbol, generator)
return
type, info = ast[0].type, ast[0].info
if type == "keyword":
if info == "begin":
GenSeq(ast, symbol, generator, isTail)
elif info == "if":
GenIf(ast, symbol, generator, isTail)
elif info == "let":
GenLet(ast, symbol, generator, isTail)
elif info == "lambda":
GenLambda(ast, symbol, generator, isTail)
elif info == "lambda_v":
GenLambdaV(ast, symbol, generator, isTail)
elif info == "define":
GenDefine(ast, symbol, generator, isTail)
elif type == "symbol":
if info in Symbol2BinOp:
GenBinOp(ast, symbol, generator, isTail)
elif info in Symbol2UnOp:
GenUnOp(ast, symbol, generator, isTail)
else:
GenCall(ast, symbol, generator, isTail)
else:
assert 0
def SinglarExp(ast, symbol, generator):
assert not isinstance(ast, list)
if ast.type == "symbol":
symbol.genLoadSymbol(ast.info)
elif ast.type in ("string", "number"):
index = generator.consts.addLiteral(ast.info)
generator.gen((OpLoadConst, index))
else:
assert 0
def GenSeq(ast, symbol, generator, isTail=False):
""" (begin expr+ ) """
assert ast[0].type == "keyword", ast[0].info == "begin"
for exp in ast[1:-1]:
GenExp(exp, symbol, generator)
generator.gen((OpPop, 1))
# Value of a seq is last value of its expr.
last = ast[-1]
GenExp(last, symbol, generator, True)
def GenIf(ast, symbol, generator, isTail=False):
""" (if pred true false) """
assert ast[0].type == "keyword" and ast[0].info == "if"
assert len(ast) == 4
pred = ast[1]
true = ast[2]
false = ast[3]
GenExp(pred, symbol, generator)
falsePatch = generator.gen((OpTest, None))
GenExp(true, symbol, generator, isTail)
endPatch = generator.gen((OpJump, None))
generator.patchToHere(falsePatch)
GenExp(false, symbol, generator, isTail)
generator = generator.patchToHere(endPatch)
def GenUnOp(ast, symbol, generator, isTail=False):
""" (UnOP expr) """
assert ast[0].type == "symbol" and ast[0].info in Symbol2UnOp
assert len(ast) == 2
GenExp(ast[1], symbol, generator)
generator.gen((OpUnOp, Symbol2UnOp[ast[0].info]))
def GenBinOp(ast, symbol, generator, isTail=False):
"""(BinOp x y)"""
assert ast[0].type == "symbol" and ast[0].info in Symbol2BinOp
assert len(ast) == 3
GenExp(ast[1], symbol, generator)
GenExp(ast[2], symbol, generator)
generator.gen((OpBinOp, Symbol2BinOp[ast[0].info]))
def GenCall(ast, symbol, generator, isTail=False):
""" (func arg*) """
assert ast[0].type == 'symbol'
sym = ast[0].info
symbol.genLoadSymbol(sym)
argc = len(ast) - 1
for arg in ast[1:]:
GenExp(arg, symbol, generator)
if isTail:
generator.gen((OpTailCall, argc))
else:
generator.gen((OpCall, argc))
def GenDefine(ast, symbol, generator, isTail=False):
""" (define name expr) """
assert ast[0].type == "keyword" and ast[0].info == "define"
assert not isinstance(ast[1], list) and ast[1].type == "symbol"
assert len(ast) == 3
scope, info = symbol.add(ast[1].info)
GenExp(ast[2], symbol, generator)
if scope == "global":
generator.gen((OpSetGlobal, info))
else:
generator.gen((OpSetLocal, info))
# Value of a define expr is None
generator.gen((OpLoadConst, 0))
def GenLet(ast, symbol, generator, isTail=False):
""" (let (binds) expr """
assert ast[0].type == "keyword" and ast[0].info == "let"
assert len(ast) == 3
binds, expr = ast[1:]
proto = generator.proto
# new scope for let
symbol.push()
for item in binds:
sym, expr0 = item[:]
assert sym.type == "symbol"
GenExp(expr0, symbol, generator)
scope, info = symbol.add(sym.info)
assert scope == "local"
generator.gen((OpSetLocal, info))
GenExp(expr, symbol, generator, isTail)
# close the scope
proto.iLocalvars -= len(binds)
scope_index = (symbol.current_scope()).index
generator.gen((OpCloseUpvar, scope_index))
symbol.pop()
def GenLambdaV(ast, symbol, generator, isTail=False, name=None):
""" (lambda_v (arg1 arg2 . argv ) (body)) """
assert ast[0].type == "keyword" and ast[0].info == "lambda_v"
assert len(ast) == 3
# make a new proto.
args = ast[1]
# remove ". argv"
proto = FunctionProto(len(args) - 2, True)
proto.name = name
generator.pushProto(proto)
symbol.push(proto)
# make new symbols for arguments.
i = 0
for arg in args[:-2]:
symbol.add(arg.info, {"local": i})
i += 1
assert args[-2].info == "."
argv = args[-1].info
symbol.add(argv, {"varg": True})
GenExp(ast[2], symbol, generator, True)
generator.gen((OpRet, 1))
symbol.pop()
proto = generator.popProto()
# load closure for lambda in original proto.
generator.gen((OpBuildClosure, proto.indexInConsts))
def GenLambda(ast, symbol, generator, isTail=False, name=None):
""" (lambda (arg1 arg2) (body)) """
assert ast[0].type == "keyword" and ast[0].info in ("lambda", "lambda_v")
# make a new proto.
args = ast[1]
body = ast[2:]
proto = FunctionProto(len(args), False)
proto.name = name
generator.pushProto(proto)
symbol.push(proto)
# make new symbols for arguments.
i = 0
for argname in ast[1]:
info = {"local": i}
symbol.add(argname.info, info)
i += 1
# gen code for body
for expr in body[:-1]:
GenExp(expr, symbol, generator, True)
generator.gen((OpPop, 1))
GenExp(body[-1], symbol, generator, True)
generator.gen((OpRet, 1))
symbol.pop()
proto = generator.popProto()
# load closure for lambda in original proto.
generator.gen((OpBuildClosure, proto.indexInConsts))
class CodeGenerator(object):
def __init__(self, consts, proto):
# pc indicates address of the next instruction to be generated.
self.pc = 0
# main proto
self.proto = proto
self.insts = proto.insts
self.consts = consts
self.stack = []
pass
def gen(self, code):
self.insts.append(code)
self.pc += 1
# return address of the instruction just generated.
return self.pc - 1
def patchToHere(self, pc):
assert self.insts[pc][0] in (OpTest, OpJump)
assert self.pc >= pc
self.insts[pc] = (self.insts[pc][0], self.pc - pc)
def pushProto(self, proto):
index = self.consts.addProto(proto)
proto.indexInConsts = index
self.stack.append((self.pc, self.proto))
self.proto = proto
self.insts = proto.insts
self.pc = 0
def popProto(self):
oldProto = self.proto
self.pc, self.proto = self.stack.pop()
self.insts = self.proto.insts
return oldProto
class ConstTable(object):
def __init__(self):
self.consts = [UNDEF_VALUE]
self.literals = {}
def addProto(self, value):
self.consts.append(value)
return len(self.consts) - 1
def addLiteral(self, literal):
if literal in self.literals:
return self.literals[literal]
self.consts.append(literal)
index = len(self.consts) - 1
self.literals[literal] = index
return index
def __getitem__(self, index):
return self.consts[index]
def __iter__(self):
return iter(self.consts)
class FunctionProto(object):
def __init__(self, argc, isvarg):
# number of arguments
self.argc = argc
self.isVararg = isvarg
self.insts = []
# used to get size of localvars in frame object.
self.maxLocalvars = argc
# index of next free localvar
self.iLocalvars = argc
self.upvars = []
def adjustMaxLocalvars(self):
if self.iLocalvars > self.maxLocalvars:
self.maxLocalvars = self.iLocalvars
# FIXME: def __str__(self):
def generate(ast):
""" generate(ast) => constTable """
consts = ConstTable()
main = FunctionProto(0, False)
generator = CodeGenerator(consts, main)
symbols = SymbolTable(generator)
GenExps(ast, symbols, generator)
consts.addProto(main)
return consts