hy/hy/compiler.py

# Copyright (c) 2013 Paul Tagliamonte <paultag@debian.org>
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.

from hy.errors import HyError

from hy.models.expression import HyExpression
from hy.models.integer import HyInteger
from hy.models.string import HyString
from hy.models.symbol import HySymbol
from hy.models.list import HyList
from hy.models.dict import HyDict

import ast
import sys


class HyCompileError(HyError):
    pass


_compile_table = {}


def builds(_type):
    def _dec(fn):
        _compile_table[_type] = fn

        def shim(*args, **kwargs):
            return fn(*args, **kwargs)
        return shim
    return _dec


class HyASTCompiler(object):

    def __init__(self):
        self.returnable = False
        self.anon_fn_count = 0

    def compile(self, tree):
        for _type in _compile_table:
            if type(tree) == _type:
                return _compile_table[_type](self, tree)

        raise HyCompileError("Unknown type - `%s'" % (str(type(tree))))

    def _mangle_branch(self, tree):
        ret = []
        tree.reverse()

        if self.returnable and len(tree) > 0:
            el = tree[0]
            if not isinstance(el, ast.stmt):
                el = tree.pop(0)
                ret.append(ast.Return(value=el,
                                      lineno=el.lineno,
                                      col_offset=el.col_offset))
        ret += [ast.Expr(value=el,
                         lineno=el.lineno,
                         col_offset=el.col_offset)
                if not isinstance(el, ast.stmt) else el for el in tree]  # NOQA

        ret.reverse()
        return ret

    @builds(list)
    def compile_raw_list(self, entries):
        return [self.compile(x) for x in entries]

    @builds("do")
    @builds("progn")
    def compile_do_expression(self, expr):
        return [self.compile(x) for x in expr[1:]]

    @builds("throw")
    def compile_throw_expression(self, expr):
        expr.pop(0)
        exc = self.compile(expr.pop(0))
        return ast.Raise(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            type=exc,
            exc=exc,
            inst=None,
            tback=None)

    @builds("try")
    def compile_try_expression(self, expr):
        expr.pop(0)  # try

        if sys.version_info[0] >= 3 and sys.version_info[1] >= 3:
            # Python 3.3 features a rename of TryExcept to Try.
            Try = ast.Try
        else:
            Try = ast.TryExcept

        return Try(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            body=self._code_branch(self.compile(expr.pop(0))),
            handlers=[self.compile(s) for s in expr],
            finalbody=[],
            orelse=[])

    @builds("catch")
    def compile_catch_expression(self, expr):
        expr.pop(0)  # catch
        _type = self.compile(expr.pop(0))
        name = expr.pop(0)

        if sys.version_info[0] >= 3:
            # Python3 features a change where the Exception handler
            # moved the name from a Name() to a pure Python String type.
            #
            # We'll just make sure it's a pure "string", and let it work
            # it's magic.
            name = str(name)
        else:
            # Python2 requires an ast.Name, set to ctx Store.
            name = self._storeize(self.compile(name))

        return ast.ExceptHandler(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            type=_type,
            name=name,
            body=self._code_branch([self.compile(x) for x in expr]))

    def _code_branch(self, branch):
        if isinstance(branch, list):
            return self._mangle_branch(branch)
        return self._mangle_branch([branch])

    @builds("if")
    def compile_if_expression(self, expr):
        expr.pop(0)
        try:
            test = expr.pop(0)
        except IndexError:
            raise TypeError("if expects at least 2 arguments, got 0")
        test = self.compile(test)
        try:
            body = expr.pop(0)
        except IndexError:
            raise TypeError("if expects at least 2 arguments, got 1")
        body = self._code_branch(self.compile(body))
        orel = []
        if len(expr) > 0:
            orel = self._code_branch(self.compile(expr.pop(0)))

        return ast.If(test=test,
                      body=body,
                      orelse=orel,
                      lineno=expr.start_line,
                      col_offset=expr.start_column)

    @builds("print")
    def compile_print_expression(self, expr):
        call = expr.pop(0)  # print
        if sys.version_info[0] >= 3:
            call = self.compile(call)
            # AST changed with Python 3, we now just call it.
            return ast.Call(
                keywords=[],
                func=call,
                args=[self.compile(x) for x in expr],
                lineno=expr.start_line,
                col_offset=expr.start_column)

        return ast.Print(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            dest=None,
            values=[self.compile(x) for x in expr],
            nl=True)

    @builds("assert")
    def compile_assert_expression(self, expr):
        expr.pop(0)  # assert
        e = expr.pop(0)
        return ast.Assert(test=self.compile(e),
                          msg=None,
                          lineno=e.start_line,
                          col_offset=e.start_column)

    @builds("lambda")
    def compile_lambda_expression(self, expr):
        expr.pop(0)
        sig = expr.pop(0)
        body = expr.pop(0)
        # assert expr is empty
        return ast.Lambda(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            args=ast.arguments(args=[
                ast.Name(arg=str(x), id=str(x),
                         ctx=ast.Param(),
                         lineno=x.start_line,
                         col_offset=x.start_column)
                for x in sig],
                vararg=None,
                kwarg=None,
                defaults=[],
                kwonlyargs=[],
                kw_defaults=[]),
            body=self.compile(body))

    @builds("pass")
    def compile_pass_expression(self, expr):
        return ast.Pass(lineno=expr.start_line, col_offset=expr.start_column)

    @builds("yield")
    def compile_yield_expression(self, expr):
        expr.pop(0)
        return ast.Yield(
            value=self.compile(expr.pop(0)),
            lineno=expr.start_line,
            col_offset=expr.start_column)

    @builds("import")
    def compile_import_expression(self, expr):
        expr.pop(0)  # index
        return ast.Import(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            names=[ast.alias(name=str(x), asname=None) for x in expr])

    @builds("import_as")
    def compile_import_as_expression(self, expr):
        expr.pop(0)  # index
        modlist = [expr[i:i + 2] for i in range(0, len(expr), 2)]
        return ast.Import(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            module=str(expr.pop(0)),
            names=[ast.alias(name=str(x[0]),
                             asname=str(x[1])) for x in modlist])

    @builds("import_from")
    def compile_import_from_expression(self, expr):
        expr.pop(0)  # index
        return ast.ImportFrom(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            module=str(expr.pop(0)),
            names=[ast.alias(name=str(x), asname=None) for x in expr],
            level=0)

    @builds("get")
    def compile_index_expression(self, expr):
        expr.pop(0)  # index
        val = self.compile(expr.pop(0))  # target
        sli = self.compile(expr.pop(0))  # slice

        return ast.Subscript(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            value=val,
            slice=ast.Index(value=sli),
            ctx=ast.Load())

    @builds("slice")
    def compile_slice_expression(self, expr):
        expr.pop(0)  # index
        val = self.compile(expr.pop(0))  # target

        low = None
        if expr != []:
            low = self.compile(expr.pop(0))

        high = None
        if expr != []:
            high = self.compile(expr.pop(0))

        return ast.Subscript(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            value=val,
            slice=ast.Slice(lower=low,
                            upper=high,
                            step=None),
            ctx=ast.Load())

    @builds("assoc")
    def compile_assoc_expression(self, expr):
        expr.pop(0)  # assoc
        # (assoc foo bar baz)  => foo[bar] = baz
        target = expr.pop(0)
        key = expr.pop(0)
        val = expr.pop(0)

        return ast.Assign(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            targets=[
                ast.Subscript(
                    lineno=expr.start_line,
                    col_offset=expr.start_column,
                    value=self.compile(target),
                    slice=ast.Index(value=self.compile(key)),
                    ctx=ast.Store())],
            value=self.compile(val))

    @builds("decorate_with")
    def compile_decorate_expression(self, expr):
        expr.pop(0)  # decorate-with
        fn = self.compile(expr.pop(-1))
        if type(fn) != ast.FunctionDef:
            raise TypeError("Decorated a non-function")
        fn.decorator_list = [self.compile(x) for x in expr]
        return fn

    @builds("with_as")
    def compile_with_as_expression(self, expr):
        expr.pop(0)  # with-as
        ctx = self.compile(expr.pop(0))
        thing = self._storeize(self.compile(expr.pop(0)))

        ret = ast.With(context_expr=ctx,
                       lineno=expr.start_line,
                       col_offset=expr.start_column,
                       optional_vars=thing,
                       body=self._mangle_branch([
                           self.compile(x) for x in expr]))

        if sys.version_info[0] >= 3 and sys.version_info[1] >= 3:
            ret.items = [ast.withitem(context_expr=ctx, optional_vars=thing)]

        return ret

    @builds(",")
    def compile_tuple(self, expr):
        expr.pop(0)
        return ast.Tuple(elts=[self.compile(x) for x in expr],
                         lineno=expr.start_line,
                         col_offset=expr.start_column,
                         ctx=ast.Load())

    @builds("list_comp")
    def compile_list_comprehension(self, expr):
        # (list-comp expr (target iter) cond?)
        expr.pop(0)
        expression = expr.pop(0)
        tar_it = iter(expr.pop(0))
        targets = zip(tar_it, tar_it)

        cond = self.compile(expr.pop(0)) if expr != [] else None

        ret = ast.ListComp(
            lineno=expr.start_line,
            col_offset=expr.start_column,
            elt=self.compile(expression),
            generators=[])

        for target, iterable in targets:
            ret.generators.append(ast.comprehension(
                target=self._storeize(self.compile(target)),
                iter=self.compile(iterable),
                ifs=[]))

        if cond:
            ret.generators[-1].ifs.append(cond)

        return ret

    def _storeize(self, name):
        if isinstance(name, ast.Tuple):
            for x in name.elts:
                x.ctx = ast.Store()
        name.ctx = ast.Store()
        return name

    @builds("kwapply")
    def compile_kwapply_expression(self, expr):
        expr.pop(0)  # kwapply
        call = self.compile(expr.pop(0))
        kwargs = expr.pop(0)

        if type(call) != ast.Call:
            raise TypeError("kwapplying a non-call")

        call.keywords = [ast.keyword(arg=str(x),
                         value=self.compile(kwargs[x])) for x in kwargs]

        return call

    @builds("=")
    @builds("!=")
    @builds("<")
    @builds("<=")
    @builds(">")
    @builds(">=")
    @builds("is")
    @builds("in")
    @builds("is_not")
    @builds("not_in")
    def compile_compare_op_expression(self, expression):
        ops = {"=": ast.Eq, "!=": ast.NotEq,
               "<": ast.Lt, "<=": ast.LtE,
               ">": ast.Gt, ">=": ast.GtE,
               "is": ast.Is, "is_not": ast.IsNot,
               "in": ast.In, "not_in": ast.NotIn}

        inv = expression.pop(0)
        op = ops[inv]
        ops = [op() for x in range(1, len(expression))]
        e = expression.pop(0)

        return ast.Compare(left=self.compile(e),
                           ops=ops,
                           comparators=[self.compile(x) for x in expression],
                           lineno=e.start_line,
                           col_offset=e.start_column)

    @builds("+")
    @builds("%")
    @builds("-")
    @builds("/")
    @builds("*")
    def compile_maths_expression(self, expression):
        # operator = Mod | Pow | LShift | RShift | BitOr |
        #            BitXor | BitAnd | FloorDiv
        # (to implement list) XXX

        ops = {"+": ast.Add,
               "/": ast.Div,
               "*": ast.Mult,
               "-": ast.Sub,
               "%": ast.Mod}

        inv = expression.pop(0)
        op = ops[inv]

        left = self.compile(expression.pop(0))
        calc = None
        for child in expression:
            calc = ast.BinOp(left=left,
                             op=op(),
                             right=self.compile(child),
                             lineno=child.start_line,
                             col_offset=child.start_column)
            left = calc
        return calc

    def compile_dotted_expression(self, expr):
        ofn = expr.pop(0)  # .join

        fn = HySymbol(ofn[1:])
        fn.replace(ofn)

        obj = expr.pop(0)  # [1 2 3 4]

        return ast.Call(
            func=ast.Attribute(
                lineno=expr.start_line,
                col_offset=expr.start_column,
                value=self.compile(obj),
                attr=str(fn),
                ctx=ast.Load()),
            args=[self.compile(x) for x in expr],
            keywords=[],
            lineno=expr.start_line,
            col_offset=expr.start_column,
            starargs=None,
            kwargs=None)

    @builds(HyExpression)
    def compile_expression(self, expression):
        fn = expression[0]
        if isinstance(fn, HyString):
            if fn in _compile_table:
                return _compile_table[fn](self, expression)

            if expression[0].startswith("."):
                return self.compile_dotted_expression(expression)

        return ast.Call(func=self.compile(fn),
                        args=[self.compile(x) for x in expression[1:]],
                        keywords=[],
                        starargs=None,
                        kwargs=None,
                        lineno=expression.start_line,
                        col_offset=expression.start_column)

    @builds("def")
    @builds("setf")
    @builds("setv")
    def compile_def_expression(self, expression):
        expression.pop(0)  # "def"
        name = expression.pop(0)

        what = self.compile(expression.pop(0))

        if type(what) == ast.FunctionDef:
            # We special case a FunctionDef, since we can define by setting
            # FunctionDef's .name attribute, rather then foo == anon_fn. This
            # helps keep things clean.
            what.name = str(name)
            return what

        name = self._storeize(self.compile(name))

        return ast.Assign(
            lineno=expression.start_line,
            col_offset=expression.start_column,
            targets=[name], value=what)

    @builds("foreach")
    def compile_for_expression(self, expression):
        ret_status = self.returnable
        self.returnable = False

        expression.pop(0)  # for
        name, iterable = expression.pop(0)
        target = self._storeize(self.compile_symbol(name))
        # support stuff like:
        # (for [x [1 2 3 4]
        #       y [a b c d]] ...)

        ret = ast.For(lineno=expression.start_line,
                      col_offset=expression.start_column,
                      target=target,
                      iter=self.compile(iterable),
                      body=self._mangle_branch([
                          self.compile(x) for x in expression]),
                      orelse=[])

        self.returnable = ret_status
        return ret

    @builds(HyList)
    def compile_list(self, expr):
        return ast.List(
            elts=[self.compile(x) for x in expr],
            ctx=ast.Load(),
            lineno=expr.start_line,
            col_offset=expr.start_column)

    @builds("fn")
    def compile_fn_expression(self, expression):
        expression.pop(0)  # fn

        ret_status = self.returnable
        self.returnable = True

        self.anon_fn_count += 1
        name = "_hy_anon_fn_%d" % (self.anon_fn_count)
        sig = expression.pop(0)

        ret = ast.FunctionDef(
            name=name,
            lineno=expression.start_line,
            col_offset=expression.start_column,
            args=ast.arguments(
                args=[
                    ast.Name(
                        arg=str(x), id=str(x),
                        ctx=ast.Param(),
                        lineno=x.start_line,
                        col_offset=x.start_column)
                    for x in sig],
                vararg=None,
                kwarg=None,
                kwonlyargs=[],
                kw_defaults=[],
                defaults=[]),
            body=self._code_branch([
                self.compile(x) for x in expression]),
            decorator_list=[])

        self.returnable = ret_status
        return ret

    @builds(HyInteger)
    def compile_number(self, number):
        return ast.Num(n=int(number),  # See HyInteger above.
                       lineno=number.start_line,
                       col_offset=number.start_column)

    @builds(HySymbol)
    def compile_symbol(self, symbol):
        if "." in symbol:
            glob, local = symbol.rsplit(".", 1)
            glob = HySymbol(glob)
            glob.replace(symbol)

            return ast.Attribute(
                lineno=symbol.start_line,
                col_offset=symbol.start_column,
                value=self.compile_symbol(glob),
                attr=str(local),
                ctx=ast.Load()
            )

        return ast.Name(id=str(symbol),
                        arg=str(symbol),
                        ctx=ast.Load(),
                        lineno=symbol.start_line,
                        col_offset=symbol.start_column)

    @builds(HyString)
    def compile_string(self, string):
        return ast.Str(s=str(string), lineno=string.start_line,
                       col_offset=string.start_column)

    @builds(HyDict)
    def compile_dict(self, m):
        keys = []
        vals = []
        for entry in m:
            keys.append(self.compile(entry))
            vals.append(self.compile(m[entry]))

        return ast.Dict(
            lineno=m.start_line,
            col_offset=m.start_column,
            keys=keys,
            values=vals)


def hy_compile(tree, root=None):
    " Compile a HyObject tree into a Python AST tree. "
    compiler = HyASTCompiler()
    tlo = root
    if root is None:
        tlo = ast.Module
    ret = tlo(body=compiler._mangle_branch(compiler.compile(tree)))
    return ret