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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 collections import namedtuple
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from io import StringIO
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from keyword import iskeyword
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import tokenize
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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 tokenize.generate_tokens(readline):
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yield token
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except tokenize.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: str
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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): (string, 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 not line.endswith('\n'):
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# If the last line doesn't have a trailing newline, treat it as if
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# it does so that the cursor at the end of the line still counts
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# as being on that line.
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next_offset += 1
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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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else:
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line = ""
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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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Function calls are prioritized, so the token for the callable will be returned
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if the cursor is anywhere inside the call.
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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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names = []
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tokens = []
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call_names = []
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offsets = {1: 0} # lines start at 1
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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_line, start_col = tok.start
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end_line, end_col = tok.end
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if end_line + 1 not in offsets:
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# keep track of offsets for each line
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lines = tok.line.splitlines(True)
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for lineno, line in enumerate(lines, start_line + 1):
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if lineno not in offsets:
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offsets[lineno] = offsets[lineno-1] + len(line)
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offset = offsets[start_line]
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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 == tokenize.NAME and not iskeyword(tok.text):
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if names and tokens and tokens[-1].token == tokenize.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 == tokenize.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 tok.text == '(' and names:
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# if we are inside a function call, inspect the function
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call_names.append(names[-1])
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elif tok.text == ')' and call_names:
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call_names.pop(-1)
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tokens.append(tok)
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if offsets[end_line] + end_col > cursor_pos:
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# we found the cursor, stop reading
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break
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if call_names:
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return call_names[-1]
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elif names:
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return names[-1]
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else:
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return ''
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