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"""
yaml.py
Lexer for YAML, a human-friendly data serialization language
(http://yaml.org/).
Written by Kirill Simonov <xi@resolvent.net>.
License: Whatever suitable for inclusion into the Pygments package.
"""
from pygments.lexer import \
ExtendedRegexLexer, LexerContext, include, bygroups
from pygments.token import \
Text, Comment, Punctuation, Name, Literal
__all__ = ['YAMLLexer']
class YAMLLexerContext(LexerContext):
"""Indentation context for the YAML lexer."""
def __init__(self, *args, **kwds):
super(YAMLLexerContext, self).__init__(*args, **kwds)
self.indent_stack = []
self.indent = -1
self.next_indent = 0
self.block_scalar_indent = None
def something(TokenClass):
"""Do not produce empty tokens."""
def callback(lexer, match, context):
text = match.group()
if not text:
return
yield match.start(), TokenClass, text
context.pos = match.end()
return callback
def reset_indent(TokenClass):
"""Reset the indentation levels."""
def callback(lexer, match, context):
text = match.group()
context.indent_stack = []
context.indent = -1
context.next_indent = 0
context.block_scalar_indent = None
yield match.start(), TokenClass, text
context.pos = match.end()
return callback
def save_indent(TokenClass, start=False):
"""Save a possible indentation level."""
def callback(lexer, match, context):
text = match.group()
extra = ''
if start:
context.next_indent = len(text)
if context.next_indent < context.indent:
while context.next_indent < context.indent:
context.indent = context.indent_stack.pop()
if context.next_indent > context.indent:
extra = text[context.indent:]
text = text[:context.indent]
else:
context.next_indent += len(text)
if text:
yield match.start(), TokenClass, text
if extra:
yield match.start()+len(text), TokenClass.Error, extra
context.pos = match.end()
return callback
def set_indent(TokenClass, implicit=False):
"""Set the previously saved indentation level."""
def callback(lexer, match, context):
text = match.group()
if context.indent < context.next_indent:
context.indent_stack.append(context.indent)
context.indent = context.next_indent
if not implicit:
context.next_indent += len(text)
yield match.start(), TokenClass, text
context.pos = match.end()
return callback
def set_block_scalar_indent(TokenClass):
"""Set an explicit indentation level for a block scalar."""
def callback(lexer, match, context):
text = match.group()
context.block_scalar_indent = None
if not text:
return
increment = match.group(1)
if increment:
current_indent = max(context.indent, 0)
increment = int(increment)
context.block_scalar_indent = current_indent + increment
if text:
yield match.start(), TokenClass, text
context.pos = match.end()
return callback
def parse_block_scalar_empty_line(IndentTokenClass, ContentTokenClass):
"""Process an empty line in a block scalar."""
def callback(lexer, match, context):
text = match.group()
if (context.block_scalar_indent is None or
len(text) <= context.block_scalar_indent):
if text:
yield match.start(), IndentTokenClass, text
else:
indentation = text[:context.block_scalar_indent]
content = text[context.block_scalar_indent:]
yield match.start(), IndentTokenClass, indentation
yield (match.start()+context.block_scalar_indent,
ContentTokenClass, content)
context.pos = match.end()
return callback
def parse_block_scalar_indent(TokenClass):
"""Process indentation spaces in a block scalar."""
def callback(lexer, match, context):
text = match.group()
if context.block_scalar_indent is None:
if len(text) <= max(context.indent, 0):
context.stack.pop()
context.stack.pop()
return
context.block_scalar_indent = len(text)
else:
if len(text) < context.block_scalar_indent:
context.stack.pop()
context.stack.pop()
return
if text:
yield match.start(), TokenClass, text
context.pos = match.end()
return callback
def parse_plain_scalar_indent(TokenClass):
"""Process indentation spaces in a plain scalar."""
def callback(lexer, match, context):
text = match.group()
if len(text) <= context.indent:
context.stack.pop()
context.stack.pop()
return
if text:
yield match.start(), TokenClass, text
context.pos = match.end()
return callback
class YAMLLexer(ExtendedRegexLexer):
"""Lexer for the YAML language."""
name = 'YAML'
aliases = ['yaml']
filenames = ['*.yaml', '*.yml']
mimetypes = ['text/x-yaml']
tokens = {
# the root rules
'root': [
# ignored whitespaces
(r'[ ]+(?=#|$)', Text.Blank),
# line breaks
(r'\n+', Text.Break),
# a comment
(r'#[^\n]*', Comment.Single),
# the '%YAML' directive
(r'^%YAML(?=[ ]|$)', reset_indent(Name.Directive),
'yaml-directive'),
# the %TAG directive
(r'^%TAG(?=[ ]|$)', reset_indent(Name.Directive),
'tag-directive'),
# document start and document end indicators
(r'^(?:---|\.\.\.)(?=[ ]|$)',
reset_indent(Punctuation.Document), 'block-line'),
# indentation spaces
(r'[ ]*(?![ \t\n\r\f\v]|$)',
save_indent(Text.Indent, start=True),
('block-line', 'indentation')),
],
# trailing whitespaces after directives or a block scalar indicator
'ignored-line': [
# ignored whitespaces
(r'[ ]+(?=#|$)', Text.Blank),
# a comment
(r'#[^\n]*', Comment.Single),
# line break
(r'\n', Text.Break, '#pop:2'),
],
# the %YAML directive
'yaml-directive': [
# the version number
(r'([ ]+)([0-9]+\.[0-9]+)',
bygroups(Text.Blank, Literal.Version), 'ignored-line'),
],
# the %YAG directive
'tag-directive': [
# a tag handle and the corresponding prefix
(r'([ ]+)(!|![0-9A-Za-z_-]*!)'
r'([ ]+)(!|!?[0-9A-Za-z;/?:@&=+$,_.!~*\'()\[\]%-]+)',
bygroups(Text.Blank, Name.Type, Text.Blank, Name.Type),
'ignored-line'),
],
# block scalar indicators and indentation spaces
'indentation': [
# trailing whitespaces are ignored
(r'[ ]*$', something(Text.Blank), '#pop:2'),
# whitespaces preceding block collection indicators
(r'[ ]+(?=[?:-](?:[ ]|$))', save_indent(Text.Indent)),
# block collection indicators
(r'[?:-](?=[ ]|$)', set_indent(Punctuation.Indicator)),
# the beginning a block line
(r'[ ]*', save_indent(Text.Indent), '#pop'),
],
# an indented line in the block context
'block-line': [
# the line end
(r'[ ]*(?=#|$)', something(Text.Blank), '#pop'),
# whitespaces separating tokens
(r'[ ]+', Text.Blank),
# tags, anchors and aliases,
include('descriptors'),
# block collections and scalars
include('block-nodes'),
# flow collections and quoted scalars
include('flow-nodes'),
# a plain scalar
(r'(?=[^ \t\n\r\f\v?:,\[\]{}#&*!|>\'"%@`-]|[?:-][^ \t\n\r\f\v])',
something(Literal.Scalar.Plain),
'plain-scalar-in-block-context'),
],
# tags, anchors, aliases
'descriptors' : [
# a full-form tag
(r'!<[0-9A-Za-z;/?:@&=+$,_.!~*\'()\[\]%-]+>', Name.Type),
# a tag in the form '!', '!suffix' or '!handle!suffix'
(r'!(?:[0-9A-Za-z_-]+)?'
r'(?:![0-9A-Za-z;/?:@&=+$,_.!~*\'()\[\]%-]+)?', Name.Type),
# an anchor
(r'&[0-9A-Za-z_-]+', Name.Anchor),
# an alias
(r'\*[0-9A-Za-z_-]+', Name.Alias),
],
# block collections and scalars
'block-nodes': [
# implicit key
(r':(?=[ ]|$)', set_indent(Punctuation.Indicator, implicit=True)),
# literal and folded scalars
(r'[|>]', Punctuation.Indicator,
('block-scalar-content', 'block-scalar-header')),
],
# flow collections and quoted scalars
'flow-nodes': [
# a flow sequence
(r'\[', Punctuation.Indicator, 'flow-sequence'),
# a flow mapping
(r'\{', Punctuation.Indicator, 'flow-mapping'),
# a single-quoted scalar
(r'\'', Literal.Scalar.Flow.Quote, 'single-quoted-scalar'),
# a double-quoted scalar
(r'\"', Literal.Scalar.Flow.Quote, 'double-quoted-scalar'),
],
# the content of a flow collection
'flow-collection': [
# whitespaces
(r'[ ]+', Text.Blank),
# line breaks
(r'\n+', Text.Break),
# a comment
(r'#[^\n]*', Comment.Single),
# simple indicators
(r'[?:,]', Punctuation.Indicator),
# tags, anchors and aliases
include('descriptors'),
# nested collections and quoted scalars
include('flow-nodes'),
# a plain scalar
(r'(?=[^ \t\n\r\f\v?:,\[\]{}#&*!|>\'"%@`])',
something(Literal.Scalar.Plain),
'plain-scalar-in-flow-context'),
],
# a flow sequence indicated by '[' and ']'
'flow-sequence': [
# include flow collection rules
include('flow-collection'),
# the closing indicator
(r'\]', Punctuation.Indicator, '#pop'),
],
# a flow mapping indicated by '{' and '}'
'flow-mapping': [
# include flow collection rules
include('flow-collection'),
# the closing indicator
(r'\}', Punctuation.Indicator, '#pop'),
],
# block scalar lines
'block-scalar-content': [
# line break
(r'\n', Text.Break),
# empty line
(r'^[ ]+$',
parse_block_scalar_empty_line(Text.Indent,
Literal.Scalar.Block)),
# indentation spaces (we may leave the state here)
(r'^[ ]*', parse_block_scalar_indent(Text.Indent)),
# line content
(r'[^\n\r\f\v]+', Literal.Scalar.Block),
],
# the content of a literal or folded scalar
'block-scalar-header': [
# indentation indicator followed by chomping flag
(r'([1-9])?[+-]?(?=[ ]|$)',
set_block_scalar_indent(Punctuation.Indicator),
'ignored-line'),
# chomping flag followed by indentation indicator
(r'[+-]?([1-9])?(?=[ ]|$)',
set_block_scalar_indent(Punctuation.Indicator),
'ignored-line'),
],
# ignored and regular whitespaces in quoted scalars
'quoted-scalar-whitespaces': [
# leading and trailing whitespaces are ignored
(r'^[ ]+|[ ]+$', Text.Blank),
# line breaks are ignored
(r'\n+', Text.Break),
# other whitespaces are a part of the value
(r'[ ]+', Literal.Scalar.Flow),
],
# single-quoted scalars
'single-quoted-scalar': [
# include whitespace and line break rules
include('quoted-scalar-whitespaces'),
# escaping of the quote character
(r'\'\'', Literal.Scalar.Flow.Escape),
# regular non-whitespace characters
(r'[^ \t\n\r\f\v\']+', Literal.Scalar.Flow),
# the closing quote
(r'\'', Literal.Scalar.Flow.Quote, '#pop'),
],
# double-quoted scalars
'double-quoted-scalar': [
# include whitespace and line break rules
include('quoted-scalar-whitespaces'),
# escaping of special characters
(r'\\[0abt\tn\nvfre "\\N_LP]', Literal.Scalar.Flow.Escape),
# escape codes
(r'\\(?:x[0-9A-Fa-f]{2}|u[0-9A-Fa-f]{4}|U[0-9A-Fa-f]{8})',
Literal.Scalar.Flow.Escape),
# regular non-whitespace characters
(r'[^ \t\n\r\f\v\"\\]+', Literal.Scalar.Flow),
# the closing quote
(r'"', Literal.Scalar.Flow.Quote, '#pop'),
],
# the beginning of a new line while scanning a plain scalar
'plain-scalar-in-block-context-new-line': [
# empty lines
(r'^[ ]+$', Text.Blank),
# line breaks
(r'\n+', Text.Break),
# document start and document end indicators
(r'^(?=---|\.\.\.)', something(Punctuation.Document), '#pop:3'),
# indentation spaces (we may leave the block line state here)
(r'^[ ]*', parse_plain_scalar_indent(Text.Indent), '#pop'),
],
# a plain scalar in the block context
'plain-scalar-in-block-context': [
# the scalar ends with the ':' indicator
(r'[ ]*(?=:[ ]|:$)', something(Text.Blank), '#pop'),
# the scalar ends with whitespaces followed by a comment
(r'[ ]+(?=#)', Text.Blank, '#pop'),
# trailing whitespaces are ignored
(r'[ ]+$', Text.Blank),
# line breaks are ignored
(r'\n+', Text.Break, 'plain-scalar-in-block-context-new-line'),
# other whitespaces are a part of the value
(r'[ ]+', Literal.Scalar.Plain),
# regular non-whitespace characters
(r'(?::(?![ \t\n\r\f\v])|[^ \t\n\r\f\v:])+',
Literal.Scalar.Plain),
],
# a plain scalar is the flow context
'plain-scalar-in-flow-context': [
# the scalar ends with an indicator character
(r'[ ]*(?=[,:?\[\]{}])', something(Text.Blank), '#pop'),
# the scalar ends with a comment
(r'[ ]+(?=#)', Text.Blank, '#pop'),
# leading and trailing whitespaces are ignored
(r'^[ ]+|[ ]+$', Text.Blank),
# line breaks are ignored
(r'\n+', Text.Break),
# other whitespaces are a part of the value
(r'[ ]+', Literal.Scalar.Plain),
# regular non-whitespace characters
(r'[^ \t\n\r\f\v,:?\[\]{}]+', Literal.Scalar.Plain),
],
}
def get_tokens_unprocessed(self, text=None, context=None):
if context is None:
context = YAMLLexerContext(text, 0)
return super(YAMLLexer, self).get_tokens_unprocessed(text, context)
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