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# System library imports
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from pygments.token import Token, is_token_subtype
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class CompletionLexer(object):
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""" Uses Pygments and some auxillary information to lex code snippets for
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symbol contexts.
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"""
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# Maps Lexer names to a list of possible name separators
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separator_map = { 'C' : [ '.', '->' ],
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'C++' : [ '.', '->', '::' ],
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'Python' : [ '.' ] }
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def __init__(self, lexer):
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""" Create a CompletionLexer using the specified Pygments lexer.
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"""
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self.lexer = lexer
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def get_context(self, string):
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""" Assuming the cursor is at the end of the specified string, get the
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context (a list of names) for the symbol at cursor position.
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"""
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context = []
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reversed_tokens = list(self._lexer.get_tokens(string))
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reversed_tokens.reverse()
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# Pygments often tacks on a newline when none is specified in the input.
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# Remove this newline.
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if reversed_tokens and reversed_tokens[0][1].endswith('\n') and \
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not string.endswith('\n'):
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reversed_tokens.pop(0)
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current_op = ''
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for token, text in reversed_tokens:
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if is_token_subtype(token, Token.Name):
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# Handle a trailing separator, e.g 'foo.bar.'
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if current_op in self._name_separators:
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if not context:
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context.insert(0, '')
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# Handle non-separator operators and punction.
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elif current_op:
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break
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context.insert(0, text)
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current_op = ''
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# Pygments doesn't understand that, e.g., '->' is a single operator
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# in C++. This is why we have to build up an operator from
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# potentially several tokens.
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elif token is Token.Operator or token is Token.Punctuation:
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current_op = text + current_op
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# Break on anything that is not a Operator, Punctuation, or Name.
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else:
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break
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return context
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def get_lexer(self, lexer):
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return self._lexer
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def set_lexer(self, lexer, name_separators=None):
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self._lexer = lexer
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if name_separators is None:
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self._name_separators = self.separator_map.get(lexer.name, ['.'])
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else:
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self._name_separators = list(name_separators)
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lexer = property(get_lexer, set_lexer)
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