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1# Copyright (C) 2014 The Android Open Source Project
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#   http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14
15from common.logger              import Logger
16from file_format.checker.struct import TestExpression, TestAssertion
17
18import re
19
20def headAndTail(list):
21  return list[0], list[1:]
22
23def splitAtSeparators(expressions):
24  """ Splits a list of TestExpressions at separators. """
25  splitExpressions = []
26  wordStart = 0
27  for index, expression in enumerate(expressions):
28    if expression.variant == TestExpression.Variant.Separator:
29      splitExpressions.append(expressions[wordStart:index])
30      wordStart = index + 1
31  splitExpressions.append(expressions[wordStart:])
32  return splitExpressions
33
34def getVariable(name, variables, pos):
35  if name in variables:
36    return variables[name]
37  else:
38    Logger.testFailed("Missing definition of variable \"{}\"".format(name), pos, variables)
39
40def setVariable(name, value, variables, pos):
41  if name not in variables:
42    return variables.copyWith(name, value)
43  else:
44    Logger.testFailed("Multiple definitions of variable \"{}\"".format(name), pos, variables)
45
46def matchWords(checkerWord, stringWord, variables, pos):
47  """ Attempts to match a list of TestExpressions against a string.
48      Returns updated variable dictionary if successful and None otherwise.
49  """
50  for expression in checkerWord:
51    # If `expression` is a variable reference, replace it with the value.
52    if expression.variant == TestExpression.Variant.VarRef:
53      pattern = re.escape(getVariable(expression.name, variables, pos))
54    else:
55      pattern = expression.text
56
57    # Match the expression's regex pattern against the remainder of the word.
58    # Note: re.match will succeed only if matched from the beginning.
59    match = re.match(pattern, stringWord)
60    if not match:
61      return None
62
63    # If `expression` was a variable definition, set the variable's value.
64    if expression.variant == TestExpression.Variant.VarDef:
65      variables = setVariable(expression.name, stringWord[:match.end()], variables, pos)
66
67    # Move cursor by deleting the matched characters.
68    stringWord = stringWord[match.end():]
69
70  # Make sure the entire word matched, i.e. `stringWord` is empty.
71  if stringWord:
72    return None
73
74  return variables
75
76def MatchLines(checkerLine, stringLine, variables):
77  """ Attempts to match a CHECK line against a string. Returns variable state
78      after the match if successful and None otherwise.
79  """
80  assert checkerLine.variant != TestAssertion.Variant.Eval
81
82  checkerWords = splitAtSeparators(checkerLine.expressions)
83  stringWords = stringLine.split()
84
85  while checkerWords:
86    # Get the next run of TestExpressions which must match one string word.
87    checkerWord, checkerWords = headAndTail(checkerWords)
88
89    # Keep reading words until a match is found.
90    wordMatched = False
91    while stringWords:
92      stringWord, stringWords = headAndTail(stringWords)
93      newVariables = matchWords(checkerWord, stringWord, variables, checkerLine)
94      if newVariables is not None:
95        wordMatched = True
96        variables = newVariables
97        break
98    if not wordMatched:
99      return None
100
101  # All TestExpressions matched. Return new variable state.
102  return variables
103
104def getEvalText(expression, variables, pos):
105  if expression.variant == TestExpression.Variant.PlainText:
106    return expression.text
107  else:
108    assert expression.variant == TestExpression.Variant.VarRef
109    return getVariable(expression.name, variables, pos)
110
111def EvaluateLine(checkerLine, variables):
112  assert checkerLine.variant == TestAssertion.Variant.Eval
113  eval_string = "".join(map(lambda expr: getEvalText(expr, variables, checkerLine),
114                            checkerLine.expressions))
115  return eval(eval_string)
116