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Diffstat (limited to 'python/pyyaml/lib/yaml/scanner.py')
| -rw-r--r-- | python/pyyaml/lib/yaml/scanner.py | 1457 |
1 files changed, 1457 insertions, 0 deletions
diff --git a/python/pyyaml/lib/yaml/scanner.py b/python/pyyaml/lib/yaml/scanner.py new file mode 100644 index 0000000000..5228fad65c --- /dev/null +++ b/python/pyyaml/lib/yaml/scanner.py @@ -0,0 +1,1457 @@ + +# Scanner produces tokens of the following types: +# STREAM-START +# STREAM-END +# DIRECTIVE(name, value) +# DOCUMENT-START +# DOCUMENT-END +# BLOCK-SEQUENCE-START +# BLOCK-MAPPING-START +# BLOCK-END +# FLOW-SEQUENCE-START +# FLOW-MAPPING-START +# FLOW-SEQUENCE-END +# FLOW-MAPPING-END +# BLOCK-ENTRY +# FLOW-ENTRY +# KEY +# VALUE +# ALIAS(value) +# ANCHOR(value) +# TAG(value) +# SCALAR(value, plain, style) +# +# Read comments in the Scanner code for more details. +# + +__all__ = ['Scanner', 'ScannerError'] + +from error import MarkedYAMLError +from tokens import * + +class ScannerError(MarkedYAMLError): + pass + +class SimpleKey(object): + # See below simple keys treatment. + + def __init__(self, token_number, required, index, line, column, mark): + self.token_number = token_number + self.required = required + self.index = index + self.line = line + self.column = column + self.mark = mark + +class Scanner(object): + + def __init__(self): + """Initialize the scanner.""" + # It is assumed that Scanner and Reader will have a common descendant. + # Reader do the dirty work of checking for BOM and converting the + # input data to Unicode. It also adds NUL to the end. + # + # Reader supports the following methods + # self.peek(i=0) # peek the next i-th character + # self.prefix(l=1) # peek the next l characters + # self.forward(l=1) # read the next l characters and move the pointer. + + # Had we reached the end of the stream? + self.done = False + + # The number of unclosed '{' and '['. `flow_level == 0` means block + # context. + self.flow_level = 0 + + # List of processed tokens that are not yet emitted. + self.tokens = [] + + # Add the STREAM-START token. + self.fetch_stream_start() + + # Number of tokens that were emitted through the `get_token` method. + self.tokens_taken = 0 + + # The current indentation level. + self.indent = -1 + + # Past indentation levels. + self.indents = [] + + # Variables related to simple keys treatment. + + # A simple key is a key that is not denoted by the '?' indicator. + # Example of simple keys: + # --- + # block simple key: value + # ? not a simple key: + # : { flow simple key: value } + # We emit the KEY token before all keys, so when we find a potential + # simple key, we try to locate the corresponding ':' indicator. + # Simple keys should be limited to a single line and 1024 characters. + + # Can a simple key start at the current position? A simple key may + # start: + # - at the beginning of the line, not counting indentation spaces + # (in block context), + # - after '{', '[', ',' (in the flow context), + # - after '?', ':', '-' (in the block context). + # In the block context, this flag also signifies if a block collection + # may start at the current position. + self.allow_simple_key = True + + # Keep track of possible simple keys. This is a dictionary. The key + # is `flow_level`; there can be no more that one possible simple key + # for each level. The value is a SimpleKey record: + # (token_number, required, index, line, column, mark) + # A simple key may start with ALIAS, ANCHOR, TAG, SCALAR(flow), + # '[', or '{' tokens. + self.possible_simple_keys = {} + + # Public methods. + + def check_token(self, *choices): + # Check if the next token is one of the given types. + while self.need_more_tokens(): + self.fetch_more_tokens() + if self.tokens: + if not choices: + return True + for choice in choices: + if isinstance(self.tokens[0], choice): + return True + return False + + def peek_token(self): + # Return the next token, but do not delete if from the queue. + while self.need_more_tokens(): + self.fetch_more_tokens() + if self.tokens: + return self.tokens[0] + + def get_token(self): + # Return the next token. + while self.need_more_tokens(): + self.fetch_more_tokens() + if self.tokens: + self.tokens_taken += 1 + return self.tokens.pop(0) + + # Private methods. + + def need_more_tokens(self): + if self.done: + return False + if not self.tokens: + return True + # The current token may be a potential simple key, so we + # need to look further. + self.stale_possible_simple_keys() + if self.next_possible_simple_key() == self.tokens_taken: + return True + + def fetch_more_tokens(self): + + # Eat whitespaces and comments until we reach the next token. + self.scan_to_next_token() + + # Remove obsolete possible simple keys. + self.stale_possible_simple_keys() + + # Compare the current indentation and column. It may add some tokens + # and decrease the current indentation level. + self.unwind_indent(self.column) + + # Peek the next character. + ch = self.peek() + + # Is it the end of stream? + if ch == u'\0': + return self.fetch_stream_end() + + # Is it a directive? + if ch == u'%' and self.check_directive(): + return self.fetch_directive() + + # Is it the document start? + if ch == u'-' and self.check_document_start(): + return self.fetch_document_start() + + # Is it the document end? + if ch == u'.' and self.check_document_end(): + return self.fetch_document_end() + + # TODO: support for BOM within a stream. + #if ch == u'\uFEFF': + # return self.fetch_bom() <-- issue BOMToken + + # Note: the order of the following checks is NOT significant. + + # Is it the flow sequence start indicator? + if ch == u'[': + return self.fetch_flow_sequence_start() + + # Is it the flow mapping start indicator? + if ch == u'{': + return self.fetch_flow_mapping_start() + + # Is it the flow sequence end indicator? + if ch == u']': + return self.fetch_flow_sequence_end() + + # Is it the flow mapping end indicator? + if ch == u'}': + return self.fetch_flow_mapping_end() + + # Is it the flow entry indicator? + if ch == u',': + return self.fetch_flow_entry() + + # Is it the block entry indicator? + if ch == u'-' and self.check_block_entry(): + return self.fetch_block_entry() + + # Is it the key indicator? + if ch == u'?' and self.check_key(): + return self.fetch_key() + + # Is it the value indicator? + if ch == u':' and self.check_value(): + return self.fetch_value() + + # Is it an alias? + if ch == u'*': + return self.fetch_alias() + + # Is it an anchor? + if ch == u'&': + return self.fetch_anchor() + + # Is it a tag? + if ch == u'!': + return self.fetch_tag() + + # Is it a literal scalar? + if ch == u'|' and not self.flow_level: + return self.fetch_literal() + + # Is it a folded scalar? + if ch == u'>' and not self.flow_level: + return self.fetch_folded() + + # Is it a single quoted scalar? + if ch == u'\'': + return self.fetch_single() + + # Is it a double quoted scalar? + if ch == u'\"': + return self.fetch_double() + + # It must be a plain scalar then. + if self.check_plain(): + return self.fetch_plain() + + # No? It's an error. Let's produce a nice error message. + raise ScannerError("while scanning for the next token", None, + "found character %r that cannot start any token" + % ch.encode('utf-8'), self.get_mark()) + + # Simple keys treatment. + + def next_possible_simple_key(self): + # Return the number of the nearest possible simple key. Actually we + # don't need to loop through the whole dictionary. We may replace it + # with the following code: + # if not self.possible_simple_keys: + # return None + # return self.possible_simple_keys[ + # min(self.possible_simple_keys.keys())].token_number + min_token_number = None + for level in self.possible_simple_keys: + key = self.possible_simple_keys[level] + if min_token_number is None or key.token_number < min_token_number: + min_token_number = key.token_number + return min_token_number + + def stale_possible_simple_keys(self): + # Remove entries that are no longer possible simple keys. According to + # the YAML specification, simple keys + # - should be limited to a single line, + # - should be no longer than 1024 characters. + # Disabling this procedure will allow simple keys of any length and + # height (may cause problems if indentation is broken though). + for level in self.possible_simple_keys.keys(): + key = self.possible_simple_keys[level] + if key.line != self.line \ + or self.index-key.index > 1024: + if key.required: + raise ScannerError("while scanning a simple key", key.mark, + "could not found expected ':'", self.get_mark()) + del self.possible_simple_keys[level] + + def save_possible_simple_key(self): + # The next token may start a simple key. We check if it's possible + # and save its position. This function is called for + # ALIAS, ANCHOR, TAG, SCALAR(flow), '[', and '{'. + + # Check if a simple key is required at the current position. + required = not self.flow_level and self.indent == self.column + + # A simple key is required only if it is the first token in the current + # line. Therefore it is always allowed. + assert self.allow_simple_key or not required + + # The next token might be a simple key. Let's save it's number and + # position. + if self.allow_simple_key: + self.remove_possible_simple_key() + token_number = self.tokens_taken+len(self.tokens) + key = SimpleKey(token_number, required, + self.index, self.line, self.column, self.get_mark()) + self.possible_simple_keys[self.flow_level] = key + + def remove_possible_simple_key(self): + # Remove the saved possible key position at the current flow level. + if self.flow_level in self.possible_simple_keys: + key = self.possible_simple_keys[self.flow_level] + + if key.required: + raise ScannerError("while scanning a simple key", key.mark, + "could not found expected ':'", self.get_mark()) + + del self.possible_simple_keys[self.flow_level] + + # Indentation functions. + + def unwind_indent(self, column): + + ## In flow context, tokens should respect indentation. + ## Actually the condition should be `self.indent >= column` according to + ## the spec. But this condition will prohibit intuitively correct + ## constructions such as + ## key : { + ## } + #if self.flow_level and self.indent > column: + # raise ScannerError(None, None, + # "invalid intendation or unclosed '[' or '{'", + # self.get_mark()) + + # In the flow context, indentation is ignored. We make the scanner less + # restrictive then specification requires. + if self.flow_level: + return + + # In block context, we may need to issue the BLOCK-END tokens. + while self.indent > column: + mark = self.get_mark() + self.indent = self.indents.pop() + self.tokens.append(BlockEndToken(mark, mark)) + + def add_indent(self, column): + # Check if we need to increase indentation. + if self.indent < column: + self.indents.append(self.indent) + self.indent = column + return True + return False + + # Fetchers. + + def fetch_stream_start(self): + # We always add STREAM-START as the first token and STREAM-END as the + # last token. + + # Read the token. + mark = self.get_mark() + + # Add STREAM-START. + self.tokens.append(StreamStartToken(mark, mark, + encoding=self.encoding)) + + + def fetch_stream_end(self): + + # Set the current intendation to -1. + self.unwind_indent(-1) + + # Reset simple keys. + self.remove_possible_simple_key() + self.allow_simple_key = False + self.possible_simple_keys = {} + + # Read the token. + mark = self.get_mark() + + # Add STREAM-END. + self.tokens.append(StreamEndToken(mark, mark)) + + # The steam is finished. + self.done = True + + def fetch_directive(self): + + # Set the current intendation to -1. + self.unwind_indent(-1) + + # Reset simple keys. + self.remove_possible_simple_key() + self.allow_simple_key = False + + # Scan and add DIRECTIVE. + self.tokens.append(self.scan_directive()) + + def fetch_document_start(self): + self.fetch_document_indicator(DocumentStartToken) + + def fetch_document_end(self): + self.fetch_document_indicator(DocumentEndToken) + + def fetch_document_indicator(self, TokenClass): + + # Set the current intendation to -1. + self.unwind_indent(-1) + + # Reset simple keys. Note that there could not be a block collection + # after '---'. + self.remove_possible_simple_key() + self.allow_simple_key = False + + # Add DOCUMENT-START or DOCUMENT-END. + start_mark = self.get_mark() + self.forward(3) + end_mark = self.get_mark() + self.tokens.append(TokenClass(start_mark, end_mark)) + + def fetch_flow_sequence_start(self): + self.fetch_flow_collection_start(FlowSequenceStartToken) + + def fetch_flow_mapping_start(self): + self.fetch_flow_collection_start(FlowMappingStartToken) + + def fetch_flow_collection_start(self, TokenClass): + + # '[' and '{' may start a simple key. + self.save_possible_simple_key() + + # Increase the flow level. + self.flow_level += 1 + + # Simple keys are allowed after '[' and '{'. + self.allow_simple_key = True + + # Add FLOW-SEQUENCE-START or FLOW-MAPPING-START. + start_mark = self.get_mark() + self.forward() + end_mark = self.get_mark() + self.tokens.append(TokenClass(start_mark, end_mark)) + + def fetch_flow_sequence_end(self): + self.fetch_flow_collection_end(FlowSequenceEndToken) + + def fetch_flow_mapping_end(self): + self.fetch_flow_collection_end(FlowMappingEndToken) + + def fetch_flow_collection_end(self, TokenClass): + + # Reset possible simple key on the current level. + self.remove_possible_simple_key() + + # Decrease the flow level. + self.flow_level -= 1 + + # No simple keys after ']' or '}'. + self.allow_simple_key = False + + # Add FLOW-SEQUENCE-END or FLOW-MAPPING-END. + start_mark = self.get_mark() + self.forward() + end_mark = self.get_mark() + self.tokens.append(TokenClass(start_mark, end_mark)) + + def fetch_flow_entry(self): + + # Simple keys are allowed after ','. + self.allow_simple_key = True + + # Reset possible simple key on the current level. + self.remove_possible_simple_key() + + # Add FLOW-ENTRY. + start_mark = self.get_mark() + self.forward() + end_mark = self.get_mark() + self.tokens.append(FlowEntryToken(start_mark, end_mark)) + + def fetch_block_entry(self): + + # Block context needs additional checks. + if not self.flow_level: + + # Are we allowed to start a new entry? + if not self.allow_simple_key: + raise ScannerError(None, None, + "sequence entries are not allowed here", + self.get_mark()) + + # We may need to add BLOCK-SEQUENCE-START. + if self.add_indent(self.column): + mark = self.get_mark() + self.tokens.append(BlockSequenceStartToken(mark, mark)) + + # It's an error for the block entry to occur in the flow context, + # but we let the parser detect this. + else: + pass + + # Simple keys are allowed after '-'. + self.allow_simple_key = True + + # Reset possible simple key on the current level. + self.remove_possible_simple_key() + + # Add BLOCK-ENTRY. + start_mark = self.get_mark() + self.forward() + end_mark = self.get_mark() + self.tokens.append(BlockEntryToken(start_mark, end_mark)) + + def fetch_key(self): + + # Block context needs additional checks. + if not self.flow_level: + + # Are we allowed to start a key (not nessesary a simple)? + if not self.allow_simple_key: + raise ScannerError(None, None, + "mapping keys are not allowed here", + self.get_mark()) + + # We may need to add BLOCK-MAPPING-START. + if self.add_indent(self.column): + mark = self.get_mark() + self.tokens.append(BlockMappingStartToken(mark, mark)) + + # Simple keys are allowed after '?' in the block context. + self.allow_simple_key = not self.flow_level + + # Reset possible simple key on the current level. + self.remove_possible_simple_key() + + # Add KEY. + start_mark = self.get_mark() + self.forward() + end_mark = self.get_mark() + self.tokens.append(KeyToken(start_mark, end_mark)) + + def fetch_value(self): + + # Do we determine a simple key? + if self.flow_level in self.possible_simple_keys: + + # Add KEY. + key = self.possible_simple_keys[self.flow_level] + del self.possible_simple_keys[self.flow_level] + self.tokens.insert(key.token_number-self.tokens_taken, + KeyToken(key.mark, key.mark)) + + # If this key starts a new block mapping, we need to add + # BLOCK-MAPPING-START. + if not self.flow_level: + if self.add_indent(key.column): + self.tokens.insert(key.token_number-self.tokens_taken, + BlockMappingStartToken(key.mark, key.mark)) + + # There cannot be two simple keys one after another. + self.allow_simple_key = False + + # It must be a part of a complex key. + else: + + # Block context needs additional checks. + # (Do we really need them? They will be catched by the parser + # anyway.) + if not self.flow_level: + + # We are allowed to start a complex value if and only if + # we can start a simple key. + if not self.allow_simple_key: + raise ScannerError(None, None, + "mapping values are not allowed here", + self.get_mark()) + + # If this value starts a new block mapping, we need to add + # BLOCK-MAPPING-START. It will be detected as an error later by + # the parser. + if not self.flow_level: + if self.add_indent(self.column): + mark = self.get_mark() + self.tokens.append(BlockMappingStartToken(mark, mark)) + + # Simple keys are allowed after ':' in the block context. + self.allow_simple_key = not self.flow_level + + # Reset possible simple key on the current level. + self.remove_possible_simple_key() + + # Add VALUE. + start_mark = self.get_mark() + self.forward() + end_mark = self.get_mark() + self.tokens.append(ValueToken(start_mark, end_mark)) + + def fetch_alias(self): + + # ALIAS could be a simple key. + self.save_possible_simple_key() + + # No simple keys after ALIAS. + self.allow_simple_key = False + + # Scan and add ALIAS. + self.tokens.append(self.scan_anchor(AliasToken)) + + def fetch_anchor(self): + + # ANCHOR could start a simple key. + self.save_possible_simple_key() + + # No simple keys after ANCHOR. + self.allow_simple_key = False + + # Scan and add ANCHOR. + self.tokens.append(self.scan_anchor(AnchorToken)) + + def fetch_tag(self): + + # TAG could start a simple key. + self.save_possible_simple_key() + + # No simple keys after TAG. + self.allow_simple_key = False + + # Scan and add TAG. + self.tokens.append(self.scan_tag()) + + def fetch_literal(self): + self.fetch_block_scalar(style='|') + + def fetch_folded(self): + self.fetch_block_scalar(style='>') + + def fetch_block_scalar(self, style): + + # A simple key may follow a block scalar. + self.allow_simple_key = True + + # Reset possible simple key on the current level. + self.remove_possible_simple_key() + + # Scan and add SCALAR. + self.tokens.append(self.scan_block_scalar(style)) + + def fetch_single(self): + self.fetch_flow_scalar(style='\'') + + def fetch_double(self): + self.fetch_flow_scalar(style='"') + + def fetch_flow_scalar(self, style): + + # A flow scalar could be a simple key. + self.save_possible_simple_key() + + # No simple keys after flow scalars. + self.allow_simple_key = False + + # Scan and add SCALAR. + self.tokens.append(self.scan_flow_scalar(style)) + + def fetch_plain(self): + + # A plain scalar could be a simple key. + self.save_possible_simple_key() + + # No simple keys after plain scalars. But note that `scan_plain` will + # change this flag if the scan is finished at the beginning of the + # line. + self.allow_simple_key = False + + # Scan and add SCALAR. May change `allow_simple_key`. + self.tokens.append(self.scan_plain()) + + # Checkers. + + def check_directive(self): + + # DIRECTIVE: ^ '%' ... + # The '%' indicator is already checked. + if self.column == 0: + return True + + def check_document_start(self): + + # DOCUMENT-START: ^ '---' (' '|'\n') + if self.column == 0: + if self.prefix(3) == u'---' \ + and self.peek(3) in u'\0 \t\r\n\x85\u2028\u2029': + return True + + def check_document_end(self): + + # DOCUMENT-END: ^ '...' (' '|'\n') + if self.column == 0: + if self.prefix(3) == u'...' \ + and self.peek(3) in u'\0 \t\r\n\x85\u2028\u2029': + return True + + def check_block_entry(self): + + # BLOCK-ENTRY: '-' (' '|'\n') + return self.peek(1) in u'\0 \t\r\n\x85\u2028\u2029' + + def check_key(self): + + # KEY(flow context): '?' + if self.flow_level: + return True + + # KEY(block context): '?' (' '|'\n') + else: + return self.peek(1) in u'\0 \t\r\n\x85\u2028\u2029' + + def check_value(self): + + # VALUE(flow context): ':' + if self.flow_level: + return True + + # VALUE(block context): ':' (' '|'\n') + else: + return self.peek(1) in u'\0 \t\r\n\x85\u2028\u2029' + + def check_plain(self): + + # A plain scalar may start with any non-space character except: + # '-', '?', ':', ',', '[', ']', '{', '}', + # '#', '&', '*', '!', '|', '>', '\'', '\"', + # '%', '@', '`'. + # + # It may also start with + # '-', '?', ':' + # if it is followed by a non-space character. + # + # Note that we limit the last rule to the block context (except the + # '-' character) because we want the flow context to be space + # independent. + ch = self.peek() + return ch not in u'\0 \t\r\n\x85\u2028\u2029-?:,[]{}#&*!|>\'\"%@`' \ + or (self.peek(1) not in u'\0 \t\r\n\x85\u2028\u2029' + and (ch == u'-' or (not self.flow_level and ch in u'?:'))) + + # Scanners. + + def scan_to_next_token(self): + # We ignore spaces, line breaks and comments. + # If we find a line break in the block context, we set the flag + # `allow_simple_key` on. + # The byte order mark is stripped if it's the first character in the + # stream. We do not yet support BOM inside the stream as the + # specification requires. Any such mark will be considered as a part + # of the document. + # + # TODO: We need to make tab handling rules more sane. A good rule is + # Tabs cannot precede tokens + # BLOCK-SEQUENCE-START, BLOCK-MAPPING-START, BLOCK-END, + # KEY(block), VALUE(block), BLOCK-ENTRY + # So the checking code is + # if <TAB>: + # self.allow_simple_keys = False + # We also need to add the check for `allow_simple_keys == True` to + # `unwind_indent` before issuing BLOCK-END. + # Scanners for block, flow, and plain scalars need to be modified. + + if self.index == 0 and self.peek() == u'\uFEFF': + self.forward() + found = False + while not found: + while self.peek() == u' ': + self.forward() + if self.peek() == u'#': + while self.peek() not in u'\0\r\n\x85\u2028\u2029': + self.forward() + if self.scan_line_break(): + if not self.flow_level: + self.allow_simple_key = True + else: + found = True + + def scan_directive(self): + # See the specification for details. + start_mark = self.get_mark() + self.forward() + name = self.scan_directive_name(start_mark) + value = None + if name == u'YAML': + value = self.scan_yaml_directive_value(start_mark) + end_mark = self.get_mark() + elif name == u'TAG': + value = self.scan_tag_directive_value(start_mark) + end_mark = self.get_mark() + else: + end_mark = self.get_mark() + while self.peek() not in u'\0\r\n\x85\u2028\u2029': + self.forward() + self.scan_directive_ignored_line(start_mark) + return DirectiveToken(name, value, start_mark, end_mark) + + def scan_directive_name(self, start_mark): + # See the specification for details. + length = 0 + ch = self.peek(length) + while u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z' \ + or ch in u'-_': + length += 1 + ch = self.peek(length) + if not length: + raise ScannerError("while scanning a directive", start_mark, + "expected alphabetic or numeric character, but found %r" + % ch.encode('utf-8'), self.get_mark()) + value = self.prefix(length) + self.forward(length) + ch = self.peek() + if ch not in u'\0 \r\n\x85\u2028\u2029': + raise ScannerError("while scanning a directive", start_mark, + "expected alphabetic or numeric character, but found %r" + % ch.encode('utf-8'), self.get_mark()) + return value + + def scan_yaml_directive_value(self, start_mark): + # See the specification for details. + while self.peek() == u' ': + self.forward() + major = self.scan_yaml_directive_number(start_mark) + if self.peek() != '.': + raise ScannerError("while scanning a directive", start_mark, + "expected a digit or '.', but found %r" + % self.peek().encode('utf-8'), + self.get_mark()) + self.forward() + minor = self.scan_yaml_directive_number(start_mark) + if self.peek() not in u'\0 \r\n\x85\u2028\u2029': + raise ScannerError("while scanning a directive", start_mark, + "expected a digit or ' ', but found %r" + % self.peek().encode('utf-8'), + self.get_mark()) + return (major, minor) + + def scan_yaml_directive_number(self, start_mark): + # See the specification for details. + ch = self.peek() + if not (u'0' <= ch <= u'9'): + raise ScannerError("while scanning a directive", start_mark, + "expected a digit, but found %r" % ch.encode('utf-8'), + self.get_mark()) + length = 0 + while u'0' <= self.peek(length) <= u'9': + length += 1 + value = int(self.prefix(length)) + self.forward(length) + return value + + def scan_tag_directive_value(self, start_mark): + # See the specification for details. + while self.peek() == u' ': + self.forward() + handle = self.scan_tag_directive_handle(start_mark) + while self.peek() == u' ': + self.forward() + prefix = self.scan_tag_directive_prefix(start_mark) + return (handle, prefix) + + def scan_tag_directive_handle(self, start_mark): + # See the specification for details. + value = self.scan_tag_handle('directive', start_mark) + ch = self.peek() + if ch != u' ': + raise ScannerError("while scanning a directive", start_mark, + "expected ' ', but found %r" % ch.encode('utf-8'), + self.get_mark()) + return value + + def scan_tag_directive_prefix(self, start_mark): + # See the specification for details. + value = self.scan_tag_uri('directive', start_mark) + ch = self.peek() + if ch not in u'\0 \r\n\x85\u2028\u2029': + raise ScannerError("while scanning a directive", start_mark, + "expected ' ', but found %r" % ch.encode('utf-8'), + self.get_mark()) + return value + + def scan_directive_ignored_line(self, start_mark): + # See the specification for details. + while self.peek() == u' ': + self.forward() + if self.peek() == u'#': + while self.peek() not in u'\0\r\n\x85\u2028\u2029': + self.forward() + ch = self.peek() + if ch not in u'\0\r\n\x85\u2028\u2029': + raise ScannerError("while scanning a directive", start_mark, + "expected a comment or a line break, but found %r" + % ch.encode('utf-8'), self.get_mark()) + self.scan_line_break() + + def scan_anchor(self, TokenClass): + # The specification does not restrict characters for anchors and + # aliases. This may lead to problems, for instance, the document: + # [ *alias, value ] + # can be interpteted in two ways, as + # [ "value" ] + # and + # [ *alias , "value" ] + # Therefore we restrict aliases to numbers and ASCII letters. + start_mark = self.get_mark() + indicator = self.peek() + if indicator == u'*': + name = 'alias' + else: + name = 'anchor' + self.forward() + length = 0 + ch = self.peek(length) + while u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z' \ + or ch in u'-_': + length += 1 + ch = self.peek(length) + if not length: + raise ScannerError("while scanning an %s" % name, start_mark, + "expected alphabetic or numeric character, but found %r" + % ch.encode('utf-8'), self.get_mark()) + value = self.prefix(length) + self.forward(length) + ch = self.peek() + if ch not in u'\0 \t\r\n\x85\u2028\u2029?:,]}%@`': + raise ScannerError("while scanning an %s" % name, start_mark, + "expected alphabetic or numeric character, but found %r" + % ch.encode('utf-8'), self.get_mark()) + end_mark = self.get_mark() + return TokenClass(value, start_mark, end_mark) + + def scan_tag(self): + # See the specification for details. + start_mark = self.get_mark() + ch = self.peek(1) + if ch == u'<': + handle = None + self.forward(2) + suffix = self.scan_tag_uri('tag', start_mark) + if self.peek() != u'>': + raise ScannerError("while parsing a tag", start_mark, + "expected '>', but found %r" % self.peek().encode('utf-8'), + self.get_mark()) + self.forward() + elif ch in u'\0 \t\r\n\x85\u2028\u2029': + handle = None + suffix = u'!' + self.forward() + else: + length = 1 + use_handle = False + while ch not in u'\0 \r\n\x85\u2028\u2029': + if ch == u'!': + use_handle = True + break + length += 1 + ch = self.peek(length) + handle = u'!' + if use_handle: + handle = self.scan_tag_handle('tag', start_mark) + else: + handle = u'!' + self.forward() + suffix = self.scan_tag_uri('tag', start_mark) + ch = self.peek() + if ch not in u'\0 \r\n\x85\u2028\u2029': + raise ScannerError("while scanning a tag", start_mark, + "expected ' ', but found %r" % ch.encode('utf-8'), + self.get_mark()) + value = (handle, suffix) + end_mark = self.get_mark() + return TagToken(value, start_mark, end_mark) + + def scan_block_scalar(self, style): + # See the specification for details. + + if style == '>': + folded = True + else: + folded = False + + chunks = [] + start_mark = self.get_mark() + + # Scan the header. + self.forward() + chomping, increment = self.scan_block_scalar_indicators(start_mark) + self.scan_block_scalar_ignored_line(start_mark) + + # Determine the indentation level and go to the first non-empty line. + min_indent = self.indent+1 + if min_indent < 1: + min_indent = 1 + if increment is None: + breaks, max_indent, end_mark = self.scan_block_scalar_indentation() + indent = max(min_indent, max_indent) + else: + indent = min_indent+increment-1 + breaks, end_mark = self.scan_block_scalar_breaks(indent) + line_break = u'' + + # Scan the inner part of the block scalar. + while self.column == indent and self.peek() != u'\0': + chunks.extend(breaks) + leading_non_space = self.peek() not in u' \t' + length = 0 + while self.peek(length) not in u'\0\r\n\x85\u2028\u2029': + length += 1 + chunks.append(self.prefix(length)) + self.forward(length) + line_break = self.scan_line_break() + breaks, end_mark = self.scan_block_scalar_breaks(indent) + if self.column == indent and self.peek() != u'\0': + + # Unfortunately, folding rules are ambiguous. + # + # This is the folding according to the specification: + + if folded and line_break == u'\n' \ + and leading_non_space and self.peek() not in u' \t': + if not breaks: + chunks.append(u' ') + else: + chunks.append(line_break) + + # This is Clark Evans's interpretation (also in the spec + # examples): + # + #if folded and line_break == u'\n': + # if not breaks: + # if self.peek() not in ' \t': + # chunks.append(u' ') + # else: + # chunks.append(line_break) + #else: + # chunks.append(line_break) + else: + break + + # Chomp the tail. + if chomping is not False: + chunks.append(line_break) + if chomping is True: + chunks.extend(breaks) + + # We are done. + return ScalarToken(u''.join(chunks), False, start_mark, end_mark, + style) + + def scan_block_scalar_indicators(self, start_mark): + # See the specification for details. + chomping = None + increment = None + ch = self.peek() + if ch in u'+-': + if ch == '+': + chomping = True + else: + chomping = False + self.forward() + ch = self.peek() + if ch in u'0123456789': + increment = int(ch) + if increment == 0: + raise ScannerError("while scanning a block scalar", start_mark, + "expected indentation indicator in the range 1-9, but found 0", + self.get_mark()) + self.forward() + elif ch in u'0123456789': + increment = int(ch) + if increment == 0: + raise ScannerError("while scanning a block scalar", start_mark, + "expected indentation indicator in the range 1-9, but found 0", + self.get_mark()) + self.forward() + ch = self.peek() + if ch in u'+-': + if ch == '+': + chomping = True + else: + chomping = False + self.forward() + ch = self.peek() + if ch not in u'\0 \r\n\x85\u2028\u2029': + raise ScannerError("while scanning a block scalar", start_mark, + "expected chomping or indentation indicators, but found %r" + % ch.encode('utf-8'), self.get_mark()) + return chomping, increment + + def scan_block_scalar_ignored_line(self, start_mark): + # See the specification for details. + while self.peek() == u' ': + self.forward() + if self.peek() == u'#': + while self.peek() not in u'\0\r\n\x85\u2028\u2029': + self.forward() + ch = self.peek() + if ch not in u'\0\r\n\x85\u2028\u2029': + raise ScannerError("while scanning a block scalar", start_mark, + "expected a comment or a line break, but found %r" + % ch.encode('utf-8'), self.get_mark()) + self.scan_line_break() + + def scan_block_scalar_indentation(self): + # See the specification for details. + chunks = [] + max_indent = 0 + end_mark = self.get_mark() + while self.peek() in u' \r\n\x85\u2028\u2029': + if self.peek() != u' ': + chunks.append(self.scan_line_break()) + end_mark = self.get_mark() + else: + self.forward() + if self.column > max_indent: + max_indent = self.column + return chunks, max_indent, end_mark + + def scan_block_scalar_breaks(self, indent): + # See the specification for details. + chunks = [] + end_mark = self.get_mark() + while self.column < indent and self.peek() == u' ': + self.forward() + while self.peek() in u'\r\n\x85\u2028\u2029': + chunks.append(self.scan_line_break()) + end_mark = self.get_mark() + while self.column < indent and self.peek() == u' ': + self.forward() + return chunks, end_mark + + def scan_flow_scalar(self, style): + # See the specification for details. + # Note that we loose indentation rules for quoted scalars. Quoted + # scalars don't need to adhere indentation because " and ' clearly + # mark the beginning and the end of them. Therefore we are less + # restrictive then the specification requires. We only need to check + # that document separators are not included in scalars. + if style == '"': + double = True + else: + double = False + chunks = [] + start_mark = self.get_mark() + quote = self.peek() + self.forward() + chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark)) + while self.peek() != quote: + chunks.extend(self.scan_flow_scalar_spaces(double, start_mark)) + chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark)) + self.forward() + end_mark = self.get_mark() + return ScalarToken(u''.join(chunks), False, start_mark, end_mark, + style) + + ESCAPE_REPLACEMENTS = { + u'0': u'\0', + u'a': u'\x07', + u'b': u'\x08', + u't': u'\x09', + u'\t': u'\x09', + u'n': u'\x0A', + u'v': u'\x0B', + u'f': u'\x0C', + u'r': u'\x0D', + u'e': u'\x1B', + u' ': u'\x20', + u'\"': u'\"', + u'\\': u'\\', + u'N': u'\x85', + u'_': u'\xA0', + u'L': u'\u2028', + u'P': u'\u2029', + } + + ESCAPE_CODES = { + u'x': 2, + u'u': 4, + u'U': 8, + } + + def scan_flow_scalar_non_spaces(self, double, start_mark): + # See the specification for details. + chunks = [] + while True: + length = 0 + while self.peek(length) not in u'\'\"\\\0 \t\r\n\x85\u2028\u2029': + length += 1 + if length: + chunks.append(self.prefix(length)) + self.forward(length) + ch = self.peek() + if not double and ch == u'\'' and self.peek(1) == u'\'': + chunks.append(u'\'') + self.forward(2) + elif (double and ch == u'\'') or (not double and ch in u'\"\\'): + chunks.append(ch) + self.forward() + elif double and ch == u'\\': + self.forward() + ch = self.peek() + if ch in self.ESCAPE_REPLACEMENTS: + chunks.append(self.ESCAPE_REPLACEMENTS[ch]) + self.forward() + elif ch in self.ESCAPE_CODES: + length = self.ESCAPE_CODES[ch] + self.forward() + for k in range(length): + if self.peek(k) not in u'0123456789ABCDEFabcdef': + raise ScannerError("while scanning a double-quoted scalar", start_mark, + "expected escape sequence of %d hexdecimal numbers, but found %r" % + (length, self.peek(k).encode('utf-8')), self.get_mark()) + code = int(self.prefix(length), 16) + chunks.append(unichr(code)) + self.forward(length) + elif ch in u'\r\n\x85\u2028\u2029': + self.scan_line_break() + chunks.extend(self.scan_flow_scalar_breaks(double, start_mark)) + else: + raise ScannerError("while scanning a double-quoted scalar", start_mark, + "found unknown escape character %r" % ch.encode('utf-8'), self.get_mark()) + else: + return chunks + + def scan_flow_scalar_spaces(self, double, start_mark): + # See the specification for details. + chunks = [] + length = 0 + while self.peek(length) in u' \t': + length += 1 + whitespaces = self.prefix(length) + self.forward(length) + ch = self.peek() + if ch == u'\0': + raise ScannerError("while scanning a quoted scalar", start_mark, + "found unexpected end of stream", self.get_mark()) + elif ch in u'\r\n\x85\u2028\u2029': + line_break = self.scan_line_break() + breaks = self.scan_flow_scalar_breaks(double, start_mark) + if line_break != u'\n': + chunks.append(line_break) + elif not breaks: + chunks.append(u' ') + chunks.extend(breaks) + else: + chunks.append(whitespaces) + return chunks + + def scan_flow_scalar_breaks(self, double, start_mark): + # See the specification for details. + chunks = [] + while True: + # Instead of checking indentation, we check for document + # separators. + prefix = self.prefix(3) + if (prefix == u'---' or prefix == u'...') \ + and self.peek(3) in u'\0 \t\r\n\x85\u2028\u2029': + raise ScannerError("while scanning a quoted scalar", start_mark, + "found unexpected document separator", self.get_mark()) + while self.peek() in u' \t': + self.forward() + if self.peek() in u'\r\n\x85\u2028\u2029': + chunks.append(self.scan_line_break()) + else: + return chunks + + def scan_plain(self): + # See the specification for details. + # We add an additional restriction for the flow context: + # plain scalars in the flow context cannot contain ',', ':' and '?'. + # We also keep track of the `allow_simple_key` flag here. + # Indentation rules are loosed for the flow context. + chunks = [] + start_mark = self.get_mark() + end_mark = start_mark + indent = self.indent+1 + # We allow zero indentation for scalars, but then we need to check for + # document separators at the beginning of the line. + #if indent == 0: + # indent = 1 + spaces = [] + while True: + length = 0 + if self.peek() == u'#': + break + while True: + ch = self.peek(length) + if ch in u'\0 \t\r\n\x85\u2028\u2029' \ + or (not self.flow_level and ch == u':' and + self.peek(length+1) in u'\0 \t\r\n\x85\u2028\u2029') \ + or (self.flow_level and ch in u',:?[]{}'): + break + length += 1 + # It's not clear what we should do with ':' in the flow context. + if (self.flow_level and ch == u':' + and self.peek(length+1) not in u'\0 \t\r\n\x85\u2028\u2029,[]{}'): + self.forward(length) + raise ScannerError("while scanning a plain scalar", start_mark, + "found unexpected ':'", self.get_mark(), + "Please check http://pyyaml.org/wiki/YAMLColonInFlowContext for details.") + if length == 0: + break + self.allow_simple_key = False + chunks.extend(spaces) + chunks.append(self.prefix(length)) + self.forward(length) + end_mark = self.get_mark() + spaces = self.scan_plain_spaces(indent, start_mark) + if not spaces or self.peek() == u'#' \ + or (not self.flow_level and self.column < indent): + break + return ScalarToken(u''.join(chunks), True, start_mark, end_mark) + + def scan_plain_spaces(self, indent, start_mark): + # See the specification for details. + # The specification is really confusing about tabs in plain scalars. + # We just forbid them completely. Do not use tabs in YAML! + chunks = [] + length = 0 + while self.peek(length) in u' ': + length += 1 + whitespaces = self.prefix(length) + self.forward(length) + ch = self.peek() + if ch in u'\r\n\x85\u2028\u2029': + line_break = self.scan_line_break() + self.allow_simple_key = True + prefix = self.prefix(3) + if (prefix == u'---' or prefix == u'...') \ + and self.peek(3) in u'\0 \t\r\n\x85\u2028\u2029': + return + breaks = [] + while self.peek() in u' \r\n\x85\u2028\u2029': + if self.peek() == ' ': + self.forward() + else: + breaks.append(self.scan_line_break()) + prefix = self.prefix(3) + if (prefix == u'---' or prefix == u'...') \ + and self.peek(3) in u'\0 \t\r\n\x85\u2028\u2029': + return + if line_break != u'\n': + chunks.append(line_break) + elif not breaks: + chunks.append(u' ') + chunks.extend(breaks) + elif whitespaces: + chunks.append(whitespaces) + return chunks + + def scan_tag_handle(self, name, start_mark): + # See the specification for details. + # For some strange reasons, the specification does not allow '_' in + # tag handles. I have allowed it anyway. + ch = self.peek() + if ch != u'!': + raise ScannerError("while scanning a %s" % name, start_mark, + "expected '!', but found %r" % ch.encode('utf-8'), + self.get_mark()) + length = 1 + ch = self.peek(length) + if ch != u' ': + while u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z' \ + or ch in u'-_': + length += 1 + ch = self.peek(length) + if ch != u'!': + self.forward(length) + raise ScannerError("while scanning a %s" % name, start_mark, + "expected '!', but found %r" % ch.encode('utf-8'), + self.get_mark()) + length += 1 + value = self.prefix(length) + self.forward(length) + return value + + def scan_tag_uri(self, name, start_mark): + # See the specification for details. + # Note: we do not check if URI is well-formed. + chunks = [] + length = 0 + ch = self.peek(length) + while u'0' <= ch <= u'9' or u'A' <= ch <= u'Z' or u'a' <= ch <= u'z' \ + or ch in u'-;/?:@&=+$,_.!~*\'()[]%': + if ch == u'%': + chunks.append(self.prefix(length)) + self.forward(length) + length = 0 + chunks.append(self.scan_uri_escapes(name, start_mark)) + else: + length += 1 + ch = self.peek(length) + if length: + chunks.append(self.prefix(length)) + self.forward(length) + length = 0 + if not chunks: + raise ScannerError("while parsing a %s" % name, start_mark, + "expected URI, but found %r" % ch.encode('utf-8'), + self.get_mark()) + return u''.join(chunks) + + def scan_uri_escapes(self, name, start_mark): + # See the specification for details. + bytes = [] + mark = self.get_mark() + while self.peek() == u'%': + self.forward() + for k in range(2): + if self.peek(k) not in u'0123456789ABCDEFabcdef': + raise ScannerError("while scanning a %s" % name, start_mark, + "expected URI escape sequence of 2 hexdecimal numbers, but found %r" % + (self.peek(k).encode('utf-8')), self.get_mark()) + bytes.append(chr(int(self.prefix(2), 16))) + self.forward(2) + try: + value = unicode(''.join(bytes), 'utf-8') + except UnicodeDecodeError, exc: + raise ScannerError("while scanning a %s" % name, start_mark, str(exc), mark) + return value + + def scan_line_break(self): + # Transforms: + # '\r\n' : '\n' + # '\r' : '\n' + # '\n' : '\n' + # '\x85' : '\n' + # '\u2028' : '\u2028' + # '\u2029 : '\u2029' + # default : '' + ch = self.peek() + if ch in u'\r\n\x85': + if self.prefix(2) == u'\r\n': + self.forward(2) + else: + self.forward() + return u'\n' + elif ch in u'\u2028\u2029': + self.forward() + return ch + return u'' + +#try: +# import psyco +# psyco.bind(Scanner) +#except ImportError: +# pass + |