| 1 | #!/usr/bin/env python2
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| 2 | # Copyright 2016 Andy Chu. All rights reserved.
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| 3 | # Licensed under the Apache License, Version 2.0 (the "License");
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| 4 | # you may not use this file except in compliance with the License.
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| 5 | # You may obtain a copy of the License at
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| 6 | #
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| 7 | # http://www.apache.org/licenses/LICENSE-2.0
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| 8 | """
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| 9 | bool_parse.py - Parse boolean expressions.
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| 10 |
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| 11 | In contrast to test / [, the parsing of [[ expressions is done BEFORE
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| 12 | evaluation. So we are parsing a list of Word instances to an AST, rather than
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| 13 | a list of strings.
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| 14 |
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| 15 | Grammar from http://compilers.iecc.com/crenshaw/tutor6.txt, adapted to ANTLR
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| 16 | syntax.
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| 17 |
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| 18 | Expr : Term (OR Term)*
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| 19 | Term : Negated (AND Negated)*
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| 20 | Negated : '!'? Factor
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| 21 | Factor : WORD
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| 22 | | UNARY_OP WORD
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| 23 | | WORD BINARY_OP WORD
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| 24 | | '(' Expr ')'
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| 25 |
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| 26 | OR = || -o
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| 27 | AND = && -a
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| 28 | WORD = any word
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| 29 | UNARY_OP: -z -n, etc.
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| 30 | BINARY_OP: -gt, -ot, ==, etc.
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| 31 | """
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| 32 |
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| 33 | from _devbuild.gen.id_kind_asdl import Id, Kind
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| 34 | #from _devbuild.gen.id_kind_asdl import Id_str, Kind_str # for debugging
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| 35 | from _devbuild.gen.types_asdl import lex_mode_t, lex_mode_e
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| 36 | from _devbuild.gen.syntax_asdl import (loc, word_t, word_e, bool_expr,
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| 37 | bool_expr_t, Token)
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| 38 | from core.error import p_die
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| 39 | from display import ui
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| 40 | from frontend import consts
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| 41 | from mycpp.mylib import log
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| 42 | from osh import word_
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| 43 |
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| 44 | from typing import List, Optional, Tuple, TYPE_CHECKING
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| 45 | if TYPE_CHECKING:
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| 46 | from osh.word_parse import WordEmitter
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| 47 |
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| 48 | # import libc # for regex_parse
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| 49 |
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| 50 | _ = log
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| 51 |
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| 52 |
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| 53 | class BoolParser(object):
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| 54 | """Parses [[ at compile time and [ at runtime."""
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| 55 |
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| 56 | def __init__(self, w_parser):
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| 57 | # type: (WordEmitter) -> None
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| 58 | self.w_parser = w_parser
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| 59 | # Either one word or two words for lookahead
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| 60 | self.words = [] # type: List[word_t]
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| 61 |
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| 62 | self.cur_word = None # type: Optional[word_t]
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| 63 | self.bool_id = Id.Undefined_Tok
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| 64 | self.bool_kind = Kind.Undefined
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| 65 |
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| 66 | def _NextOne(self, lex_mode=lex_mode_e.DBracket):
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| 67 | # type: (lex_mode_t) -> None
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| 68 | n = len(self.words)
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| 69 | if n == 2:
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| 70 | assert lex_mode == lex_mode_e.DBracket
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| 71 | self.words[0] = self.words[1]
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| 72 | self.cur_word = self.words[0]
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| 73 | self.words.pop()
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| 74 | elif n in (0, 1):
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| 75 | w = self.w_parser.ReadWord(lex_mode) # may raise
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| 76 | if n == 0:
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| 77 | self.words.append(w)
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| 78 | else:
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| 79 | self.words[0] = w
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| 80 | self.cur_word = w
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| 81 |
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| 82 | assert self.cur_word is not None
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| 83 | self.bool_id = word_.BoolId(self.cur_word)
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| 84 | self.bool_kind = consts.GetKind(self.bool_id)
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| 85 | #log('--- word %s', self.cur_word)
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| 86 | #log('bool_id %s %s %s', Id_str(self.bool_id), Kind_str(self.bool_kind), lex_mode)
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| 87 |
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| 88 | def _Next(self, lex_mode=lex_mode_e.DBracket):
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| 89 | # type: (lex_mode_t) -> None
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| 90 | """Advance to the next token, skipping newlines.
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| 91 |
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| 92 | We don't handle newlines in the lexer because we want the
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| 93 | newline after ]] to be Id.Op_Newline rather than Id.WS_Newline.
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| 94 | It's more complicated if it's Id.WS_Newline -- we might have to
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| 95 | unread tokens, etc.
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| 96 | """
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| 97 | while True:
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| 98 | self._NextOne(lex_mode=lex_mode)
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| 99 | if self.bool_id != Id.Op_Newline:
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| 100 | break
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| 101 |
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| 102 | def _LookAhead(self):
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| 103 | # type: () -> word_t
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| 104 | n = len(self.words)
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| 105 | if n != 1:
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| 106 | raise AssertionError(n)
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| 107 |
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| 108 | w = self.w_parser.ReadWord(lex_mode_e.DBracket) # may raise
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| 109 | self.words.append(w) # Save it for _Next()
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| 110 | return w
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| 111 |
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| 112 | def Parse(self):
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| 113 | # type: () -> Tuple[bool_expr_t, Token]
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| 114 | self._Next()
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| 115 |
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| 116 | node = self.ParseExpr()
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| 117 | if self.bool_id != Id.Lit_DRightBracket:
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| 118 | #p_die("Expected ]], got %r", self.cur_word, word=self.cur_word)
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| 119 | # NOTE: This might be better as unexpected token, since ]] doesn't always
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| 120 | # make sense.
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| 121 | p_die('Expected ]]', loc.Word(self.cur_word))
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| 122 |
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| 123 | # Extract the ']]' keyword and return it's token for location tracking
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| 124 | right = word_.LiteralToken(self.cur_word)
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| 125 | assert right is not None
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| 126 |
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| 127 | return node, right
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| 128 |
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| 129 | def _TestAtEnd(self):
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| 130 | # type: () -> bool
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| 131 | """For unit tests only."""
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| 132 | return self.bool_id == Id.Lit_DRightBracket
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| 133 |
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| 134 | def ParseForBuiltin(self):
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| 135 | # type: () -> bool_expr_t
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| 136 | """For test builtin."""
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| 137 | self._Next()
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| 138 |
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| 139 | node = self.ParseExpr()
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| 140 | if self.bool_id != Id.Eof_Real:
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| 141 | p_die('Unexpected trailing word %s' % word_.Pretty(self.cur_word),
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| 142 | loc.Word(self.cur_word))
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| 143 |
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| 144 | return node
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| 145 |
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| 146 | def ParseExpr(self):
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| 147 | # type: () -> bool_expr_t
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| 148 | """
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| 149 | Iterative:
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| 150 | Expr : Term (OR Term)*
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| 151 |
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| 152 | Right recursion:
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| 153 | Expr : Term (OR Expr)?
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| 154 | """
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| 155 | left = self.ParseTerm()
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| 156 | # [[ uses || but [ uses -o
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| 157 | if self.bool_id in (Id.Op_DPipe, Id.BoolUnary_o):
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| 158 | self._Next()
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| 159 | right = self.ParseExpr()
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| 160 | return bool_expr.LogicalOr(left, right)
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| 161 | else:
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| 162 | return left
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| 163 |
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| 164 | def ParseTerm(self):
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| 165 | # type: () -> bool_expr_t
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| 166 | """
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| 167 | Term : Negated (AND Negated)*
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| 168 |
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| 169 | Right recursion:
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| 170 | Term : Negated (AND Term)?
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| 171 | """
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| 172 | left = self.ParseNegatedFactor()
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| 173 | # [[ uses && but [ uses -a
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| 174 | if self.bool_id in (Id.Op_DAmp, Id.BoolUnary_a):
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| 175 | self._Next()
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| 176 | right = self.ParseTerm()
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| 177 | return bool_expr.LogicalAnd(left, right)
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| 178 | else:
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| 179 | return left
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| 180 |
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| 181 | def ParseNegatedFactor(self):
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| 182 | # type: () -> bool_expr_t
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| 183 | """
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| 184 | Negated : '!'? Factor
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| 185 | """
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| 186 | if self.bool_id == Id.KW_Bang:
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| 187 | self._Next()
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| 188 | child = self.ParseFactor()
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| 189 | return bool_expr.LogicalNot(child)
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| 190 | else:
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| 191 | return self.ParseFactor()
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| 192 |
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| 193 | def ParseFactor(self):
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| 194 | # type: () -> bool_expr_t
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| 195 | """
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| 196 | Factor : WORD
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| 197 | | UNARY_OP WORD
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| 198 | | WORD =~ Regex
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| 199 | | WORD BINARY_OP WORD
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| 200 | | '(' Expr ')'
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| 201 |
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| 202 | Note: this grammar is ambiguous, and the design of the 'test' builtin
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| 203 | is terrible in general.
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| 204 |
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| 205 | We roughly follow bash's ordering rules, which gives a result that
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| 206 | almost all shells agree on:
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| 207 |
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| 208 | 1. Look for ( first
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| 209 | 2. Then look ahead to see if you got Kind.BoolBinary, like =
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| 210 | 3. Then unary operators: test -d / [[ -d / ]]
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| 211 | 4. Then non-empty string tests: test foo [[ foo ]]
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| 212 | """
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| 213 | if self.bool_id == Id.Op_LParen:
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| 214 | self._Next()
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| 215 | node = self.ParseExpr() # type: bool_expr_t
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| 216 | if self.bool_id != Id.Op_RParen:
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| 217 | p_die('Expected ), got %s' % word_.Pretty(self.cur_word),
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| 218 | loc.Word(self.cur_word))
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| 219 | self._Next()
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| 220 | return node
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| 221 |
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| 222 | # Peek ahead another token.
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| 223 | t2 = self._LookAhead()
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| 224 | t2_bool_id = word_.BoolId(t2)
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| 225 | t2_bool_kind = consts.GetKind(t2_bool_id)
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| 226 |
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| 227 | #log('t2 %s / t2_bool_id %s / t2_bool_kind %s', t2, t2_bool_id, t2_bool_kind)
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| 228 | # Op for < and >, -a and -o pun
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| 229 | if t2_bool_kind == Kind.BoolBinary or t2_bool_id in (Id.Op_Less,
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| 230 | Id.Op_Great):
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| 231 | left = self.cur_word
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| 232 |
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| 233 | self._Next()
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| 234 | op = self.bool_id
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| 235 |
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| 236 | if t2_bool_id == Id.BoolBinary_EqualTilde:
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| 237 | self._Next(lex_mode=lex_mode_e.BashRegex)
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| 238 | else:
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| 239 | self._Next()
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| 240 |
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| 241 | right = self.cur_word
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| 242 | self._Next()
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| 243 |
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| 244 | tilde = word_.TildeDetect(left)
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| 245 | if tilde:
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| 246 | left = tilde
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| 247 | tilde = word_.TildeDetect(right)
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| 248 | if tilde:
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| 249 | right = tilde
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| 250 |
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| 251 | return bool_expr.Binary(op, left, right)
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| 252 |
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| 253 | if self.bool_kind == Kind.BoolUnary:
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| 254 | # Just save the type and not the token itself?
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| 255 | op = self.bool_id
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| 256 | self._Next()
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| 257 | w = self.cur_word
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| 258 | # e.g. [[ -f < ]]. But [[ -f '<' ]] is OK
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| 259 |
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| 260 | tag = w.tag()
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| 261 | if tag != word_e.Compound and tag != word_e.String:
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| 262 | p_die('Invalid argument to unary operator', loc.Word(w))
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| 263 | self._Next()
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| 264 |
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| 265 | tilde = word_.TildeDetect(w)
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| 266 | if tilde:
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| 267 | w = tilde
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| 268 |
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| 269 | node = bool_expr.Unary(op, w)
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| 270 | return node
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| 271 |
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| 272 | # [[ foo ]]
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| 273 | # Note: ( = ) and ( == ) may also hit this path, but they are NOT Kind.Word
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| 274 | if self.bool_kind != Kind.Op:
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| 275 | w = self.cur_word
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| 276 | tilde = word_.TildeDetect(w)
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| 277 | if tilde:
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| 278 | w = tilde
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| 279 | self._Next()
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| 280 | return bool_expr.WordTest(w)
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| 281 |
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| 282 | # Error for [[ ) ]]
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| 283 | # It's not WORD, UNARY_OP, or '('
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| 284 | p_die(
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| 285 | 'Unexpected token in boolean expression (%s)' %
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| 286 | ui.PrettyId(self.bool_id), loc.Word(self.cur_word))
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