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# Copyright 2019 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Utility function to parse text into an ir_pb2.Expression."""
from compiler.front_end import module_ir
from compiler.front_end import parser
from compiler.front_end import tokenizer
def parse(text):
"""Parses text as an Expression.
This parses text using the expression subset of the Emboss grammar, and
returns an ir_pb2.Expression. The expression only needs to be syntactically
valid; it will not go through symbol resolution or type checking. This
function is not intended to be called on arbitrary input; it asserts that the
text successfully parses, but does not return errors.
Arguments:
text: The text of an Emboss expression, like "4 + 5" or "$max(1, a, b)".
Returns:
An ir_pb2.Expression corresponding to the textual form.
Raises:
AssertionError if text is not a well-formed Emboss expression, and
assertions are enabled.
"""
tokens, errors = tokenizer.tokenize(text, "")
assert not errors, "{!r}".format(errors)
# tokenizer.tokenize always inserts a newline token at the end, which breaks
# expression parsing.
parse_result = parser.parse_expression(tokens[:-1])
assert not parse_result.error, "{!r}".format(parse_result.error)
return module_ir.build_ir(parse_result.parse_tree)