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diff --git a/python/pyyaml/examples/pygments-lexer/yaml.py b/python/pyyaml/examples/pygments-lexer/yaml.py
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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'[ ]*$', something(Text.Blank), '#pop:2'),
+ # whitespaces preceeding block collection indicators
+ (r'[ ]+(?=[?:-](?:[ ]|$))', 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)
+
+