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"""Token-related utilities"""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from __future__ import absolute_import, print_function
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from collections import namedtuple
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from io import StringIO
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from keyword import iskeyword
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from . import tokenize2
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from .py3compat import cast_unicode_py2
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Token = namedtuple('Token', ['token', 'text', 'start', 'end', 'line'])
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def generate_tokens(readline):
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"""wrap generate_tokens to catch EOF errors"""
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try:
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for token in tokenize2.generate_tokens(readline):
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yield token
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except tokenize2.TokenError:
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# catch EOF error
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return
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def line_at_cursor(cell, cursor_pos=0):
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"""Return the line in a cell at a given cursor position
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Used for calling line-based APIs that don't support multi-line input, yet.
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Parameters
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----------
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cell: text
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multiline block of text
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cursor_pos: integer
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the cursor position
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Returns
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-------
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(line, offset): (text, integer)
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The line with the current cursor, and the character offset of the start of the line.
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"""
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offset = 0
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lines = cell.splitlines(True)
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for line in lines:
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next_offset = offset + len(line)
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if next_offset >= cursor_pos:
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break
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offset = next_offset
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return (line, offset)
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def token_at_cursor(cell, cursor_pos=0):
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"""Get the token at a given cursor
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Used for introspection.
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Parameters
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----------
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cell : unicode
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A block of Python code
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cursor_pos : int
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The location of the cursor in the block where the token should be found
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"""
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cell = cast_unicode_py2(cell)
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names = []
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tokens = []
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offset = 0
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for tup in generate_tokens(StringIO(cell).readline):
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tok = Token(*tup)
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# token, text, start, end, line = tup
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start_col = tok.start[1]
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end_col = tok.end[1]
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# allow '|foo' to find 'foo' at the beginning of a line
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boundary = cursor_pos + 1 if start_col == 0 else cursor_pos
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if offset + start_col >= boundary:
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# current token starts after the cursor,
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# don't consume it
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break
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if tok.token == tokenize2.NAME and not iskeyword(tok.text):
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if names and tokens and tokens[-1].token == tokenize2.OP and tokens[-1].text == '.':
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names[-1] = "%s.%s" % (names[-1], tok.text)
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else:
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names.append(tok.text)
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elif tok.token == tokenize2.OP:
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if tok.text == '=' and names:
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# don't inspect the lhs of an assignment
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names.pop(-1)
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if offset + end_col > cursor_pos:
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# we found the cursor, stop reading
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break
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tokens.append(tok)
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if tok.token == tokenize2.NEWLINE:
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offset += len(tok.line)
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if names:
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return names[-1]
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else:
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return ''
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