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211 lines (191 loc) · 8.9 KB
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package pythonparse
import fastparse._
import Lexical.kw
/**
* Python's expression grammar. This is stuff that can be used within a larger
* expression. Everything here ignores whitespace and does not care about
* indentation
*
* Manually transcribed from https://docs.python.org/2/reference/grammar.html
*/
object Expressions {
implicit def whitespace(cfg: P[_]): P[Unit] = Lexical.wscomment(cfg)
def tuplize(xs: Seq[Ast.expr]) = xs match{
case Seq(x) => x
case xs => Ast.expr.Tuple(xs, Ast.expr_context.Load)
}
def NAME[_: P]: P[Ast.identifier] = Lexical.identifier
def NUMBER[_: P]: P[Ast.expr.Num] = P( Lexical.floatnumber | Lexical.longinteger | Lexical.integer | Lexical.imagnumber ).map(Ast.expr.Num)
def STRING[_: P]: P[Ast.string] = Lexical.stringliteral
def test[_: P]: P[Ast.expr] = {
def ternary = P( or_test ~ (kw("if") ~ or_test ~ kw("else") ~ test).? ).map{
case (x, None) => x
case (x, Some((test, neg))) => Ast.expr.IfExp(test, x, neg)
}
P( ternary | lambdef )
}
def or_test[_: P] = P( and_test.rep(1, sep = kw("or")) ).map{
case Seq(x) => x
case xs => Ast.expr.BoolOp(Ast.boolop.Or, xs)
}
def and_test[_: P] = P( not_test.rep(1, sep = kw("and")) ).map{
case Seq(x) => x
case xs => Ast.expr.BoolOp(Ast.boolop.And, xs)
}
def not_test[_: P]: P[Ast.expr] = P( (kw("not") ~ not_test).map(Ast.expr.UnaryOp(Ast.unaryop.Not, _)) | comparison )
def comparison[_: P]: P[Ast.expr] = P( expr ~ (comp_op ~ expr).rep ).map{
case (lhs, Nil) => lhs
case (lhs, chunks) =>
val (ops, vals) = chunks.unzip
Ast.expr.Compare(lhs, ops, vals)
}
// Common operators, mapped from their
// strings to their type-safe representations
def op[T, _: P](s: => P[Unit], rhs: T) = s.!.map(_ => rhs)
def LShift[_: P] = op("<<", Ast.operator.LShift)
def RShift[_: P] = op(">>", Ast.operator.RShift)
def Lt[_: P] = op("<", Ast.cmpop.Lt)
def Gt[_: P] = op(">", Ast.cmpop.Gt)
def Eq[_: P] = op("==", Ast.cmpop.Eq)
def GtE[_: P] = op(">=", Ast.cmpop.GtE)
def LtE[_: P] = op("<=", Ast.cmpop.LtE)
def NotEq[_: P] = op("<>" | "!=", Ast.cmpop.NotEq)
def In[_: P] = op(kw("in"), Ast.cmpop.In)
def NotIn[_: P] = op(kw("not") ~ kw("in"), Ast.cmpop.NotIn)
def Is[_: P] = op(kw("is"), Ast.cmpop.Is)
def IsNot[_: P] = op(kw("is") ~ kw("not"), Ast.cmpop.IsNot)
def comp_op[_: P] = P( LtE|GtE|Eq|Gt|Lt|NotEq|In|NotIn|IsNot|Is )
def Add[_: P] = op("+", Ast.operator.Add)
def Sub[_: P] = op("-", Ast.operator.Sub)
def Pow[_: P] = op("**", Ast.operator.Pow)
def Mult[_: P] = op("*", Ast.operator.Mult)
def Div[_: P] = op("/", Ast.operator.Div)
def Mod[_: P] = op("%", Ast.operator.Mod)
def FloorDiv[_: P] = op("//", Ast.operator.FloorDiv)
def BitOr[_: P] = op("|", Ast.operator.BitOr)
def BitAnd[_: P] = op("&", Ast.operator.BitAnd)
def BitXor[_: P] = op("^", Ast.operator.BitXor)
def UAdd[_: P] = op("+", Ast.unaryop.UAdd)
def USub[_: P] = op("-", Ast.unaryop.USub)
def Invert[_: P] = op("~", Ast.unaryop.Invert)
def unary_op[_: P] = P ( UAdd | USub | Invert )
def Unary[_: P](p: => P[Ast.expr]) =
(unary_op ~ p).map{ case (op, operand) => Ast.expr.UnaryOp(op, operand) }
def Chain[_: P](p: => P[Ast.expr], op: => P[Ast.operator]) = P( p ~ (op ~ p).rep ).map{
case (lhs, chunks) =>
chunks.foldLeft(lhs){case (lhs, (op, rhs)) =>
Ast.expr.BinOp(lhs, op, rhs)
}
}
def expr[_: P]: P[Ast.expr] = P( Chain(xor_expr, BitOr) )
def xor_expr[_: P]: P[Ast.expr] = P( Chain(and_expr, BitXor) )
def and_expr[_: P]: P[Ast.expr] = P( Chain(shift_expr, BitAnd) )
def shift_expr[_: P]: P[Ast.expr] = P( Chain(arith_expr, LShift | RShift) )
def arith_expr[_: P]: P[Ast.expr] = P( Chain(term, Add | Sub) )
def term[_: P]: P[Ast.expr] = P( Chain(factor, Mult | FloorDiv | Div | Mod ) )
def factor[_: P]: P[Ast.expr] = P( power | Unary(factor) )
def power[_: P]: P[Ast.expr] = P( atom ~ trailer.rep ~ (Pow ~ factor).? ).map{
case (lhs, trailers, rhs) =>
val left = trailers.foldLeft(lhs)((l, t) => t(l))
rhs match{
case None => left
case Some((op, right)) => Ast.expr.BinOp(left, op, right)
}
}
def atom[_: P]: P[Ast.expr] = {
def empty_tuple = ("(" ~ ")").map(_ => Ast.expr.Tuple(Nil, Ast.expr_context.Load))
def empty_list = ("[" ~ "]").map(_ => Ast.expr.List(Nil, Ast.expr_context.Load))
def empty_dict = ("{" ~ "}").map(_ => Ast.expr.Dict(Nil, Nil))
P(
empty_tuple |
empty_list |
empty_dict |
"(" ~ (yield_expr | generator | tuple | test) ~ ")" |
"[" ~ (list_comp | list) ~ "]" |
"{" ~ dictorsetmaker ~ "}" |
"`" ~ testlist1.map(x => Ast.expr.Repr(Ast.expr.Tuple(x, Ast.expr_context.Load))) ~ "`" |
STRING.rep(1).map(_.mkString).map(Ast.expr.Str) |
NAME.map(Ast.expr.Name(_, Ast.expr_context.Load)) |
NUMBER
)
}
def list_contents[_: P] = P( test.rep(1, ",") ~ ",".? )
def list[_: P] = P( list_contents ).map(Ast.expr.List(_, Ast.expr_context.Load))
def tuple_contents[_: P] = P( test ~ "," ~ list_contents.?).map { case (head, rest) => head +: rest.getOrElse(Seq.empty) }
def tuple[_: P] = P( tuple_contents).map(Ast.expr.Tuple(_, Ast.expr_context.Load))
def list_comp_contents[_: P] = P( test ~ comp_for.rep(1) )
def list_comp[_: P] = P( list_comp_contents ).map(Ast.expr.ListComp.tupled)
def generator[_: P] = P( list_comp_contents ).map(Ast.expr.GeneratorExp.tupled)
def lambdef[_: P]: P[Ast.expr.Lambda] = P( kw("lambda") ~ varargslist ~ ":" ~ test ).map(Ast.expr.Lambda.tupled)
def trailer[_: P]: P[Ast.expr => Ast.expr] = {
def call = P("(" ~ arglist ~ ")").map{ case (args, (keywords, starargs, kwargs)) => (lhs: Ast.expr) => Ast.expr.Call(lhs, args, keywords, starargs, kwargs)}
def slice = P("[" ~ subscriptlist ~ "]").map(args => (lhs: Ast.expr) => Ast.expr.Subscript(lhs, args, Ast.expr_context.Load))
def attr = P("." ~ NAME).map(id => (lhs: Ast.expr) => Ast.expr.Attribute(lhs, id, Ast.expr_context.Load))
P( call | slice | attr )
}
def subscriptlist[_: P] = P( subscript.rep(1, ",") ~ ",".? ).map{
case Seq(x) => x
case xs => Ast.slice.ExtSlice(xs)
}
def subscript[_: P]: P[Ast.slice] = {
def ellipses = P( ("." ~ "." ~ ".").map(_ => Ast.slice.Ellipsis) )
def single = P( test.map(Ast.slice.Index) )
def multi = P(test.? ~ ":" ~ test.? ~ sliceop.?).map { case (lower, upper, step) =>
Ast.slice.Slice(
lower,
upper,
step.map(_.getOrElse(Ast.expr.Name(Ast.identifier("None"), Ast.expr_context.Load)))
)
}
P( ellipses | multi | single )
}
def sliceop[_: P] = P( ":" ~ test.? )
def exprlist[_: P]: P[Seq[Ast.expr]] = P( expr.rep(1, sep = ",") ~ ",".? )
def testlist[_: P]: P[Seq[Ast.expr]] = P( test.rep(1, sep = ",") ~ ",".? )
def dictorsetmaker[_: P]: P[Ast.expr] = {
def dict_item = P( test ~ ":" ~ test )
def dict: P[Ast.expr.Dict] = P(
(dict_item.rep(1, ",") ~ ",".?).map{x =>
val (keys, values) = x.unzip
Ast.expr.Dict(keys, values)
}
)
def dict_comp = P(
(dict_item ~ comp_for.rep(1)).map(Ast.expr.DictComp.tupled)
)
def set: P[Ast.expr.Set] = P( test.rep(1, ",") ~ ",".? ).map(Ast.expr.Set)
def set_comp = P( test ~ comp_for.rep(1) ).map(Ast.expr.SetComp.tupled)
P( dict_comp | dict | set_comp | set)
}
def arglist[_: P] = {
def inits = P( (plain_argument ~ !"=").rep(0, ",") )
def later = P( named_argument.rep(0, ",") ~ ",".? ~ ("*" ~ test).? ~ ",".? ~ ("**" ~ test).? ~ ",".? ~ named_argument.rep(0, ",")).map{
case (named1, dot, star, named2) => (named1 ++ named2, dot, star )
}
P( inits ~ ",".? ~ later )
}
def plain_argument[_: P] = P( test ~ comp_for.rep ).map{
case (x, Nil) => x
case (x, gens) => Ast.expr.GeneratorExp(x, gens)
}
def named_argument[_: P] = P( NAME ~ "=" ~ test ).map(Ast.keyword.tupled)
def comp_for[_: P]: P[Ast.comprehension] = P( kw("for") ~ exprlist ~ kw("in") ~ or_test ~ comp_if.rep ).map{
case (targets, test, ifs) => Ast.comprehension(tuplize(targets), test, ifs)
}
def comp_if[_: P]: P[Ast.expr] = P( kw("if") ~ test )
def testlist1[_: P]: P[Seq[Ast.expr]] = P( test.rep(1, sep = ",") )
// not used in grammar, but may appear in "node" passed from Parser to Compiler
// def encoding_decl[_: P]: P0 = P( NAME )
def yield_expr[_: P]: P[Ast.expr.Yield] = P( kw("yield") ~ testlist.map(tuplize).? ).map(Ast.expr.Yield)
def varargslist[_: P]: P[Ast.arguments] = {
def named_arg = P( fpdef ~ ("=" ~ test).? )
def x = P( named_arg.rep(sep = ",") ~ ",".? ~ ("*" ~ NAME).? ~ ",".? ~ ("**" ~ NAME).? ).map{
case (normal_args, starargs, kwargs) =>
val (args, defaults) = normal_args.unzip
Ast.arguments(args, starargs, kwargs, defaults.flatten)
}
P( x )
}
def fpdef[_: P]: P[Ast.expr] = P( NAME.map(Ast.expr.Name(_, Ast.expr_context.Param)) | "(" ~ fplist ~ ")" )
def fplist[_: P]: P[Ast.expr] = P( fpdef.rep(sep = ",") ~ ",".? ).map(Ast.expr.Tuple(_, Ast.expr_context.Param))
}