saphyr-serde/parser/src/scanner.rs
2024-01-23 00:19:04 +01:00

2212 lines
68 KiB
Rust

#![allow(clippy::cast_possible_wrap)]
#![allow(clippy::cast_sign_loss)]
use std::collections::VecDeque;
use std::error::Error;
use std::{char, fmt};
#[derive(Clone, Copy, PartialEq, Debug, Eq)]
pub enum TEncoding {
Utf8,
}
#[derive(Clone, Copy, PartialEq, Debug, Eq)]
pub enum TScalarStyle {
Any,
Plain,
SingleQuoted,
DoubleQuoted,
Literal,
Foled,
}
/// A location in a yaml document.
#[derive(Clone, Copy, PartialEq, Debug, Eq)]
pub struct Marker {
index: usize,
line: usize,
col: usize,
}
impl Marker {
fn new(index: usize, line: usize, col: usize) -> Marker {
Marker { index, line, col }
}
/// Return the index (in bytes) of the marker in the source.
#[must_use]
pub fn index(&self) -> usize {
self.index
}
/// Return the line of the marker in the source.
#[must_use]
pub fn line(&self) -> usize {
self.line
}
/// Return the column of the marker in the source.
#[must_use]
pub fn col(&self) -> usize {
self.col
}
}
/// An error that occured while scanning.
#[derive(Clone, PartialEq, Debug, Eq)]
pub struct ScanError {
mark: Marker,
info: String,
}
impl ScanError {
/// Create a new error from a location and an error string.
#[must_use]
pub fn new(loc: Marker, info: &str) -> ScanError {
ScanError {
mark: loc,
info: info.to_owned(),
}
}
/// Return the marker pointing to the error in the source.
#[must_use]
pub fn marker(&self) -> &Marker {
&self.mark
}
/// Return the information string describing the error that happened.
#[must_use]
pub fn info(&self) -> &str {
self.info.as_ref()
}
}
impl Error for ScanError {
fn description(&self) -> &str {
self.info.as_ref()
}
fn cause(&self) -> Option<&dyn Error> {
None
}
}
impl fmt::Display for ScanError {
// col starts from 0
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
write!(
formatter,
"{} at line {} column {}",
self.info,
self.mark.line,
self.mark.col + 1
)
}
}
#[derive(Clone, PartialEq, Debug, Eq)]
pub enum TokenType {
NoToken,
/// The start of the stream. Sent first, before even [`DocumentStart`].
StreamStart(TEncoding),
/// The end of the stream, EOF.
StreamEnd,
VersionDirective(
/// Major
u32,
/// Minor
u32,
),
TagDirective(
/// Handle
String,
/// Prefix
String,
),
/// The start of a YAML document (`---`).
DocumentStart,
/// The end of a YAML document (`...`).
DocumentEnd,
/// The start of a sequence block.
///
/// Sequence blocks are arrays starting with a `-`.
BlockSequenceStart,
/// The start of a sequence mapping.
///
/// Sequence mappings are "dictionaries" with "key: value" entries.
BlockMappingStart,
/// End of the corresponding `BlockSequenceStart` or `BlockMappingStart`.
BlockEnd,
/// Start of an inline array (`[ a, b ]`).
FlowSequenceStart,
/// End of an inline array.
FlowSequenceEnd,
/// Start of an inline mapping (`{ a: b, c: d }`).
FlowMappingStart,
/// End of an inline mapping.
FlowMappingEnd,
/// An entry in a block sequence (c.f.: [`TokenType::BlockSequenceStart`]).
BlockEntry,
/// An entry in a flow sequence (c.f.: [`TokenType::FlowSequenceStart`]).
FlowEntry,
/// A key in a mapping.
Key,
/// A value in a mapping.
Value,
/// A reference to an anchor.
Alias(String),
/// A YAML anchor (`&`/`*`).
Anchor(String),
/// A YAML tag (starting with bangs `!`).
Tag(
/// The handle of the tag.
String,
/// The suffix of the tag.
String,
),
/// A regular YAML scalar.
Scalar(TScalarStyle, String),
}
#[derive(Clone, PartialEq, Debug, Eq)]
pub struct Token(pub Marker, pub TokenType);
#[derive(Clone, PartialEq, Debug, Eq)]
struct SimpleKey {
possible: bool,
required: bool,
token_number: usize,
mark: Marker,
}
impl SimpleKey {
fn new(mark: Marker) -> SimpleKey {
SimpleKey {
possible: false,
required: false,
token_number: 0,
mark,
}
}
}
/// An indentation level on the stack of indentations.
#[derive(Clone, Debug, Default)]
struct Indent {
/// The former indentation level.
indent: isize,
/// Whether, upon closing, this indents generates a `BlockEnd` token.
///
/// There are levels of indentation which do not start a block. Examples of this would be:
/// ```yaml
/// -
/// foo # ok
/// -
/// bar # ko, bar needs to be indented further than the `-`.
/// - [
/// baz, # ok
/// quux # ko, quux needs to be indented further than the '-'.
/// ] # ko, the closing bracket needs to be indented further than the `-`.
/// ```
///
/// The indentation level created by the `-` is for a single entry in the sequence. Emitting a
/// `BlockEnd` when this indentation block ends would generate one `BlockEnd` per entry in the
/// sequence, although we must have exactly one to end the sequence.
needs_block_end: bool,
}
#[derive(Debug)]
#[allow(clippy::struct_excessive_bools)]
pub struct Scanner<T> {
/// The reader, providing with characters.
rdr: T,
/// The position of the cursor within the reader.
mark: Marker,
/// Buffer for tokens to be read.
tokens: VecDeque<Token>,
/// Buffer for the next characters to consume.
buffer: VecDeque<char>,
/// The last error that happened.
error: Option<ScanError>,
/// Whether we have already emitted the `StreamStart` token.
stream_start_produced: bool,
/// Whether we have already emitted the `StreamEnd` token.
stream_end_produced: bool,
adjacent_value_allowed_at: usize,
/// Whether a simple key could potentially start at the current position.
///
/// Simple keys are the opposite of complex keys which are keys starting with `?`.
simple_key_allowed: bool,
simple_keys: Vec<SimpleKey>,
/// The current indentation level.
indent: isize,
/// List of all block indentation levels we are in (except the current one).
indents: Vec<Indent>,
/// Level of nesting of flow sequences.
flow_level: u8,
tokens_parsed: usize,
token_available: bool,
/// Whether all characters encountered since the last newline were whitespace.
leading_whitespace: bool,
/// Whether we started a flow mapping.
///
/// This is used to detect implicit flow mapping starts such as:
/// ```yaml
/// [ : foo ] # { null: "foo" }
/// ```
flow_mapping_started: bool,
/// Whether we currently are in an implicit flow mapping.
implicit_flow_mapping: bool,
}
impl<T: Iterator<Item = char>> Iterator for Scanner<T> {
type Item = Token;
fn next(&mut self) -> Option<Token> {
if self.error.is_some() {
return None;
}
match self.next_token() {
Ok(Some(tok)) => {
if std::env::var("YAMLRUST_DEBUG").is_ok() {
eprintln!(
" \x1B[;32m\u{21B3} {:?} \x1B[;36m{:?}\x1B[;m",
tok.1, tok.0
);
}
Some(tok)
}
Ok(tok) => tok,
Err(e) => {
self.error = Some(e);
None
}
}
}
}
/// Check whether the character is nil (`\0`).
#[inline]
fn is_z(c: char) -> bool {
c == '\0'
}
/// Check whether the character is a line break (`\r` or `\n`).
#[inline]
fn is_break(c: char) -> bool {
c == '\n' || c == '\r'
}
/// Check whether the character is nil or a line break (`\0`, `\r`, `\n`).
#[inline]
fn is_breakz(c: char) -> bool {
is_break(c) || is_z(c)
}
/// Check whether the character is a whitespace (` ` or `\t`).
#[inline]
fn is_blank(c: char) -> bool {
c == ' ' || c == '\t'
}
/// Check whether the character is nil, a linebreak or a whitespace.
///
/// `\0`, ` `, `\t`, `\n`, `\r`
#[inline]
fn is_blankz(c: char) -> bool {
is_blank(c) || is_breakz(c)
}
/// Check whether the character is an ascii digit.
#[inline]
fn is_digit(c: char) -> bool {
c.is_ascii_digit()
}
/// Check whether the character is a digit, letter, `_` or `-`.
#[inline]
fn is_alpha(c: char) -> bool {
matches!(c, '0'..='9' | 'a'..='z' | 'A'..='Z' | '_' | '-')
}
/// Check whether the character is a hexadecimal character (case insensitive).
#[inline]
fn is_hex(c: char) -> bool {
c.is_ascii_digit() || ('a'..='f').contains(&c) || ('A'..='F').contains(&c)
}
/// Convert the hexadecimal digit to an integer.
#[inline]
fn as_hex(c: char) -> u32 {
match c {
'0'..='9' => (c as u32) - ('0' as u32),
'a'..='f' => (c as u32) - ('a' as u32) + 10,
'A'..='F' => (c as u32) - ('A' as u32) + 10,
_ => unreachable!(),
}
}
/// Check whether the character is a YAML flow character (one of `,[]{}`).
#[inline]
fn is_flow(c: char) -> bool {
matches!(c, ',' | '[' | ']' | '{' | '}')
}
/// Check whether the character is the BOM character.
#[inline]
fn is_bom(c: char) -> bool {
c == '\u{FEFF}'
}
/// Check whether the character is a YAML non-breaking character.
#[inline]
fn is_yaml_non_break(c: char) -> bool {
// TODO(ethiraric, 28/12/2023): is_printable
!is_break(c) && !is_bom(c)
}
/// Check whether the character is NOT a YAML whitespace (` ` / `\t`).
#[inline]
fn is_yaml_non_space(c: char) -> bool {
is_yaml_non_break(c) && !is_blank(c)
}
/// Check whether the character is a valid YAML anchor name character.
#[inline]
fn is_anchor_char(c: char) -> bool {
is_yaml_non_space(c) && !is_flow(c) && !is_z(c)
}
pub type ScanResult = Result<(), ScanError>;
impl<T: Iterator<Item = char>> Scanner<T> {
/// Creates the YAML tokenizer.
pub fn new(rdr: T) -> Scanner<T> {
Scanner {
rdr,
buffer: VecDeque::new(),
mark: Marker::new(0, 1, 0),
tokens: VecDeque::new(),
error: None,
stream_start_produced: false,
stream_end_produced: false,
adjacent_value_allowed_at: 0,
simple_key_allowed: true,
simple_keys: Vec::new(),
indent: -1,
indents: Vec::new(),
flow_level: 0,
tokens_parsed: 0,
token_available: false,
leading_whitespace: true,
flow_mapping_started: false,
implicit_flow_mapping: false,
}
}
#[inline]
pub fn get_error(&self) -> Option<ScanError> {
self.error.as_ref().map(std::clone::Clone::clone)
}
/// Fill `self.buffer` with at least `count` characters.
///
/// The characters that are extracted this way are not consumed but only placed in the buffer.
#[inline]
fn lookahead(&mut self, count: usize) {
if self.buffer.len() >= count {
return;
}
for _ in 0..(count - self.buffer.len()) {
self.buffer.push_back(self.rdr.next().unwrap_or('\0'));
}
}
/// Consume the next character. Remove from buffer and update mark.
#[inline]
fn skip(&mut self) {
let c = self.buffer.pop_front().unwrap();
self.mark.index += 1;
if c == '\n' {
self.leading_whitespace = true;
self.mark.line += 1;
self.mark.col = 0;
} else {
// TODO(ethiraric, 20/12/2023): change to `self.leading_whitespace &= is_blank(c)`?
if self.leading_whitespace && !is_blank(c) {
self.leading_whitespace = false;
}
self.mark.col += 1;
}
}
/// Consume a linebreak (either CR, LF or CRLF), if any. Do nothing if there's none.
#[inline]
fn skip_line(&mut self) {
if self.buffer[0] == '\r' && self.buffer[1] == '\n' {
self.skip();
self.skip();
} else if is_break(self.buffer[0]) {
self.skip();
}
}
/// Return the next character in the buffer.
///
/// The character is not consumed.
#[inline]
fn ch(&self) -> char {
self.buffer[0]
}
/// Look for the next character and return it.
///
/// The character is not consumed.
/// Equivalent to calling [`Self::lookahead`] and [`Self::ch`].
#[inline]
fn look_ch(&mut self) -> char {
self.lookahead(1);
self.ch()
}
/// Consume and return the next character.
///
/// Equivalent to calling [`Self::ch`] and [`Self::skip`].
#[inline]
fn ch_skip(&mut self) -> char {
let ret = self.ch();
self.skip();
ret
}
/// Return whether the next character is `c`.
#[inline]
fn ch_is(&self, c: char) -> bool {
self.buffer[0] == c
}
#[allow(dead_code)]
#[inline]
fn eof(&self) -> bool {
self.ch_is('\0')
}
#[inline]
pub fn stream_started(&self) -> bool {
self.stream_start_produced
}
#[inline]
pub fn stream_ended(&self) -> bool {
self.stream_end_produced
}
#[inline]
pub fn mark(&self) -> Marker {
self.mark
}
// Read and consume a line break (either `\r`, `\n` or `\r\n`).
//
// A `\n` is pushed into `s`.
//
// # Panics
// If the next characters do not correspond to a line break.
#[inline]
fn read_break(&mut self, s: &mut String) {
if self.buffer[0] == '\r' && self.buffer[1] == '\n' {
s.push('\n');
self.skip();
self.skip();
} else if self.buffer[0] == '\r' || self.buffer[0] == '\n' {
s.push('\n');
self.skip();
} else {
unreachable!();
}
}
/// Insert a token at the given position.
fn insert_token(&mut self, pos: usize, tok: Token) {
let old_len = self.tokens.len();
assert!(pos <= old_len);
self.tokens.insert(pos, tok);
}
fn allow_simple_key(&mut self) {
self.simple_key_allowed = true;
}
fn disallow_simple_key(&mut self) {
self.simple_key_allowed = false;
}
pub fn fetch_next_token(&mut self) -> ScanResult {
self.lookahead(1);
// eprintln!("--> fetch_next_token Cur {:?} {:?}", self.mark, self.ch());
if !self.stream_start_produced {
self.fetch_stream_start();
return Ok(());
}
self.skip_to_next_token()?;
if std::env::var("YAMLRUST_DEBUG").is_ok() {
eprintln!(
" \x1B[38;5;244m\u{2192} fetch_next_token after whitespace {:?} {:?}\x1B[m",
self.mark,
self.ch()
);
}
self.stale_simple_keys()?;
let mark = self.mark;
self.unroll_indent(mark.col as isize);
self.lookahead(4);
if is_z(self.ch()) {
self.fetch_stream_end()?;
return Ok(());
}
// Is it a directive?
if self.mark.col == 0 && self.ch_is('%') {
return self.fetch_directive();
}
if self.mark.col == 0
&& self.buffer[0] == '-'
&& self.buffer[1] == '-'
&& self.buffer[2] == '-'
&& is_blankz(self.buffer[3])
{
self.fetch_document_indicator(TokenType::DocumentStart)?;
return Ok(());
}
if self.mark.col == 0
&& self.buffer[0] == '.'
&& self.buffer[1] == '.'
&& self.buffer[2] == '.'
&& is_blankz(self.buffer[3])
{
self.fetch_document_indicator(TokenType::DocumentEnd)?;
return Ok(());
}
let c = self.buffer[0];
let nc = self.buffer[1];
match c {
'[' => self.fetch_flow_collection_start(TokenType::FlowSequenceStart),
'{' => self.fetch_flow_collection_start(TokenType::FlowMappingStart),
']' => self.fetch_flow_collection_end(TokenType::FlowSequenceEnd),
'}' => self.fetch_flow_collection_end(TokenType::FlowMappingEnd),
',' => self.fetch_flow_entry(),
'-' if is_blankz(nc) => self.fetch_block_entry(),
'?' if is_blankz(nc) => self.fetch_key(),
':' if is_blankz(nc)
|| (self.flow_level > 0
&& (is_flow(nc) || self.mark.index == self.adjacent_value_allowed_at)) =>
{
self.fetch_value()
}
// Is it an alias?
'*' => self.fetch_anchor(true),
// Is it an anchor?
'&' => self.fetch_anchor(false),
'!' => self.fetch_tag(),
// Is it a literal scalar?
'|' if self.flow_level == 0 => self.fetch_block_scalar(true),
// Is it a folded scalar?
'>' if self.flow_level == 0 => self.fetch_block_scalar(false),
'\'' => self.fetch_flow_scalar(true),
'"' => self.fetch_flow_scalar(false),
// plain scalar
'-' if !is_blankz(nc) => self.fetch_plain_scalar(),
':' | '?' if !is_blankz(nc) && self.flow_level == 0 => self.fetch_plain_scalar(),
'%' | '@' | '`' => Err(ScanError::new(
self.mark,
&format!("unexpected character: `{c}'"),
)),
_ => self.fetch_plain_scalar(),
}
}
pub fn next_token(&mut self) -> Result<Option<Token>, ScanError> {
if self.stream_end_produced {
return Ok(None);
}
if !self.token_available {
self.fetch_more_tokens()?;
}
let t = self.tokens.pop_front().unwrap();
self.token_available = false;
self.tokens_parsed += 1;
if let TokenType::StreamEnd = t.1 {
self.stream_end_produced = true;
}
Ok(Some(t))
}
pub fn fetch_more_tokens(&mut self) -> ScanResult {
let mut need_more;
loop {
if self.tokens.is_empty() {
need_more = true;
} else {
need_more = false;
self.stale_simple_keys()?;
for sk in &self.simple_keys {
if sk.possible && sk.token_number == self.tokens_parsed {
need_more = true;
break;
}
}
}
if !need_more {
break;
}
self.fetch_next_token()?;
}
self.token_available = true;
Ok(())
}
fn stale_simple_keys(&mut self) -> ScanResult {
for sk in &mut self.simple_keys {
if sk.possible
&& (sk.mark.line < self.mark.line || sk.mark.index + 1024 < self.mark.index)
{
if sk.required {
return Err(ScanError::new(self.mark, "simple key expect ':'"));
}
sk.possible = false;
}
}
Ok(())
}
/// Skip over all whitespace and comments until the next token.
///
/// # Errors
/// This function returns an error if a tabulation is encountered where there should not be
/// one.
fn skip_to_next_token(&mut self) -> ScanResult {
loop {
// TODO(chenyh) BOM
match self.look_ch() {
' ' => self.skip(),
// Tabs may not be used as indentation.
// "Indentation" only exists as long as a block is started, but does not exist
// inside of flow-style constructs. Tabs are allowed as part of leading
// whitespaces outside of indentation.
// If a flow-style construct is in an indented block, its contents must still be
// indented. Also, tabs are allowed anywhere in it if it has no content.
'\t' if self.is_within_block()
&& self.leading_whitespace
&& (self.mark.col as isize) < self.indent =>
{
self.skip_ws_to_eol(SkipTabs::Yes);
// If we have content on that line with a tab, return an error.
if !is_breakz(self.ch()) {
return Err(ScanError::new(
self.mark,
"tabs disallowed within this context (block indentation)",
));
}
}
'\t' => self.skip(),
'\n' | '\r' => {
self.lookahead(2);
self.skip_line();
if self.flow_level == 0 {
self.allow_simple_key();
}
}
'#' => {
while !is_breakz(self.ch()) {
self.skip();
self.lookahead(1);
}
}
_ => break,
}
}
Ok(())
}
/// Skip over YAML whitespace (` `, `\n`, `\r`).
///
/// # Errors
/// This function returns an error if no whitespace was found.
fn skip_yaml_whitespace(&mut self) -> ScanResult {
let mut need_whitespace = true;
loop {
match self.look_ch() {
' ' => {
self.skip();
need_whitespace = false;
}
'\n' | '\r' => {
self.lookahead(2);
self.skip_line();
if self.flow_level == 0 {
self.allow_simple_key();
}
need_whitespace = false;
}
'#' => {
while !is_breakz(self.ch()) {
self.skip();
self.lookahead(1);
}
}
_ => break,
}
}
if need_whitespace {
Err(ScanError::new(self.mark(), "expected whitespace"))
} else {
Ok(())
}
}
/// Skip yaml whitespace at most up to eol. Also skips comments.
fn skip_ws_to_eol(&mut self, skip_tabs: SkipTabs) -> SkipTabs {
let mut encountered_tab = false;
let mut has_yaml_ws = false;
loop {
match self.look_ch() {
' ' => {
has_yaml_ws = true;
self.skip();
}
'\t' if skip_tabs != SkipTabs::No => {
encountered_tab = true;
self.skip();
}
'#' => {
while !is_breakz(self.look_ch()) {
self.skip();
}
}
_ => break,
}
}
SkipTabs::Result(encountered_tab, has_yaml_ws)
}
fn fetch_stream_start(&mut self) {
let mark = self.mark;
self.indent = -1;
self.stream_start_produced = true;
self.allow_simple_key();
self.tokens
.push_back(Token(mark, TokenType::StreamStart(TEncoding::Utf8)));
self.simple_keys.push(SimpleKey::new(Marker::new(0, 0, 0)));
}
fn fetch_stream_end(&mut self) -> ScanResult {
// force new line
if self.mark.col != 0 {
self.mark.col = 0;
self.mark.line += 1;
}
self.unroll_indent(-1);
self.remove_simple_key()?;
self.disallow_simple_key();
self.tokens
.push_back(Token(self.mark, TokenType::StreamEnd));
Ok(())
}
fn fetch_directive(&mut self) -> ScanResult {
self.unroll_indent(-1);
self.remove_simple_key()?;
self.disallow_simple_key();
let tok = self.scan_directive()?;
self.tokens.push_back(tok);
Ok(())
}
fn scan_directive(&mut self) -> Result<Token, ScanError> {
let start_mark = self.mark;
self.skip();
let name = self.scan_directive_name()?;
let tok = match name.as_ref() {
"YAML" => self.scan_version_directive_value(&start_mark)?,
"TAG" => self.scan_tag_directive_value(&start_mark)?,
// XXX This should be a warning instead of an error
_ => {
// skip current line
self.lookahead(1);
while !is_breakz(self.ch()) {
self.skip();
self.lookahead(1);
}
// XXX return an empty TagDirective token
Token(
start_mark,
TokenType::TagDirective(String::new(), String::new()),
)
// return Err(ScanError::new(start_mark,
// "while scanning a directive, found unknown directive name"))
}
};
self.lookahead(1);
while is_blank(self.ch()) {
self.skip();
self.lookahead(1);
}
if self.ch() == '#' {
while !is_breakz(self.ch()) {
self.skip();
self.lookahead(1);
}
}
if !is_breakz(self.ch()) {
return Err(ScanError::new(
start_mark,
"while scanning a directive, did not find expected comment or line break",
));
}
// Eat a line break
if is_break(self.ch()) {
self.lookahead(2);
self.skip_line();
}
Ok(tok)
}
fn scan_version_directive_value(&mut self, mark: &Marker) -> Result<Token, ScanError> {
self.lookahead(1);
while is_blank(self.ch()) {
self.skip();
self.lookahead(1);
}
let major = self.scan_version_directive_number(mark)?;
if self.ch() != '.' {
return Err(ScanError::new(
*mark,
"while scanning a YAML directive, did not find expected digit or '.' character",
));
}
self.skip();
let minor = self.scan_version_directive_number(mark)?;
Ok(Token(*mark, TokenType::VersionDirective(major, minor)))
}
fn scan_directive_name(&mut self) -> Result<String, ScanError> {
let start_mark = self.mark;
let mut string = String::new();
self.lookahead(1);
while is_alpha(self.ch()) {
string.push(self.ch());
self.skip();
self.lookahead(1);
}
if string.is_empty() {
return Err(ScanError::new(
start_mark,
"while scanning a directive, could not find expected directive name",
));
}
if !is_blankz(self.ch()) {
return Err(ScanError::new(
start_mark,
"while scanning a directive, found unexpected non-alphabetical character",
));
}
Ok(string)
}
fn scan_version_directive_number(&mut self, mark: &Marker) -> Result<u32, ScanError> {
let mut val = 0u32;
let mut length = 0usize;
self.lookahead(1);
while is_digit(self.ch()) {
if length + 1 > 9 {
return Err(ScanError::new(
*mark,
"while scanning a YAML directive, found extremely long version number",
));
}
length += 1;
val = val * 10 + ((self.ch() as u32) - ('0' as u32));
self.skip();
self.lookahead(1);
}
if length == 0 {
return Err(ScanError::new(
*mark,
"while scanning a YAML directive, did not find expected version number",
));
}
Ok(val)
}
fn scan_tag_directive_value(&mut self, mark: &Marker) -> Result<Token, ScanError> {
self.lookahead(1);
/* Eat whitespaces. */
while is_blank(self.ch()) {
self.skip();
self.lookahead(1);
}
let handle = self.scan_tag_handle(true, mark)?;
self.lookahead(1);
/* Eat whitespaces. */
while is_blank(self.ch()) {
self.skip();
self.lookahead(1);
}
let is_secondary = handle == "!!";
let prefix = self.scan_tag_uri(true, is_secondary, "", mark)?;
self.lookahead(1);
if is_blankz(self.ch()) {
Ok(Token(*mark, TokenType::TagDirective(handle, prefix)))
} else {
Err(ScanError::new(
*mark,
"while scanning TAG, did not find expected whitespace or line break",
))
}
}
fn fetch_tag(&mut self) -> ScanResult {
self.save_simple_key()?;
self.disallow_simple_key();
let tok = self.scan_tag()?;
self.tokens.push_back(tok);
Ok(())
}
fn scan_tag(&mut self) -> Result<Token, ScanError> {
let start_mark = self.mark;
let mut handle = String::new();
let mut suffix;
// Check if the tag is in the canonical form (verbatim).
self.lookahead(2);
if self.buffer[1] == '<' {
// Eat '!<'
self.skip();
self.skip();
suffix = self.scan_tag_uri(false, false, "", &start_mark)?;
if self.ch() != '>' {
return Err(ScanError::new(
start_mark,
"while scanning a tag, did not find the expected '>'",
));
}
self.skip();
} else {
// The tag has either the '!suffix' or the '!handle!suffix'
handle = self.scan_tag_handle(false, &start_mark)?;
// Check if it is, indeed, handle.
if handle.len() >= 2 && handle.starts_with('!') && handle.ends_with('!') {
// A tag handle starting with "!!" is a secondary tag handle.
let is_secondary_handle = handle == "!!";
suffix = self.scan_tag_uri(false, is_secondary_handle, "", &start_mark)?;
} else {
suffix = self.scan_tag_uri(false, false, &handle, &start_mark)?;
handle = "!".to_owned();
// A special case: the '!' tag. Set the handle to '' and the
// suffix to '!'.
if suffix.is_empty() {
handle.clear();
suffix = "!".to_owned();
}
}
}
if is_blankz(self.look_ch()) {
// XXX: ex 7.2, an empty scalar can follow a secondary tag
Ok(Token(start_mark, TokenType::Tag(handle, suffix)))
} else {
Err(ScanError::new(
start_mark,
"while scanning a tag, did not find expected whitespace or line break",
))
}
}
fn scan_tag_handle(&mut self, directive: bool, mark: &Marker) -> Result<String, ScanError> {
let mut string = String::new();
if self.look_ch() != '!' {
return Err(ScanError::new(
*mark,
"while scanning a tag, did not find expected '!'",
));
}
string.push(self.ch_skip());
while is_alpha(self.look_ch()) {
string.push(self.ch_skip());
}
// Check if the trailing character is '!' and copy it.
if self.ch() == '!' {
string.push(self.ch_skip());
} else if directive && string != "!" {
// It's either the '!' tag or not really a tag handle. If it's a %TAG
// directive, it's an error. If it's a tag token, it must be a part of
// URI.
return Err(ScanError::new(
*mark,
"while parsing a tag directive, did not find expected '!'",
));
}
Ok(string)
}
fn scan_tag_uri(
&mut self,
directive: bool,
_is_secondary: bool,
head: &str,
mark: &Marker,
) -> Result<String, ScanError> {
let mut length = head.len();
let mut string = String::new();
// Copy the head if needed.
// Note that we don't copy the leading '!' character.
if length > 1 {
string.extend(head.chars().skip(1));
}
/*
* The set of characters that may appear in URI is as follows:
*
* '0'-'9', 'A'-'Z', 'a'-'z', '_', '-', ';', '/', '?', ':', '@', '&',
* '=', '+', '$', ',', '.', '!', '~', '*', '\'', '(', ')', '[', ']',
* '%'.
*/
while match self.look_ch() {
';' | '/' | '?' | ':' | '@' | '&' => true,
'=' | '+' | '$' | ',' | '.' | '!' | '~' | '*' | '\'' | '(' | ')' | '[' | ']' => true,
'%' => true,
c if is_alpha(c) => true,
_ => false,
} {
// Check if it is a URI-escape sequence.
if self.ch() == '%' {
string.push(self.scan_uri_escapes(directive, mark)?);
} else {
string.push(self.ch());
self.skip();
}
length += 1;
}
if length == 0 {
return Err(ScanError::new(
*mark,
"while parsing a tag, did not find expected tag URI",
));
}
Ok(string)
}
fn scan_uri_escapes(&mut self, _directive: bool, mark: &Marker) -> Result<char, ScanError> {
let mut width = 0usize;
let mut code = 0u32;
loop {
self.lookahead(3);
if !(self.ch() == '%' && is_hex(self.buffer[1]) && is_hex(self.buffer[2])) {
return Err(ScanError::new(
*mark,
"while parsing a tag, did not find URI escaped octet",
));
}
let octet = (as_hex(self.buffer[1]) << 4) + as_hex(self.buffer[2]);
if width == 0 {
width = match octet {
_ if octet & 0x80 == 0x00 => 1,
_ if octet & 0xE0 == 0xC0 => 2,
_ if octet & 0xF0 == 0xE0 => 3,
_ if octet & 0xF8 == 0xF0 => 4,
_ => {
return Err(ScanError::new(
*mark,
"while parsing a tag, found an incorrect leading UTF-8 octet",
));
}
};
code = octet;
} else {
if octet & 0xc0 != 0x80 {
return Err(ScanError::new(
*mark,
"while parsing a tag, found an incorrect trailing UTF-8 octet",
));
}
code = (code << 8) + octet;
}
self.skip();
self.skip();
self.skip();
width -= 1;
if width == 0 {
break;
}
}
match char::from_u32(code) {
Some(ch) => Ok(ch),
None => Err(ScanError::new(
*mark,
"while parsing a tag, found an invalid UTF-8 codepoint",
)),
}
}
fn fetch_anchor(&mut self, alias: bool) -> ScanResult {
self.save_simple_key()?;
self.disallow_simple_key();
let tok = self.scan_anchor(alias)?;
self.tokens.push_back(tok);
Ok(())
}
fn scan_anchor(&mut self, alias: bool) -> Result<Token, ScanError> {
let mut string = String::new();
let start_mark = self.mark;
self.skip();
while is_anchor_char(self.look_ch()) {
string.push(self.ch());
self.skip();
}
if string.is_empty() {
return Err(ScanError::new(start_mark, "while scanning an anchor or alias, did not find expected alphabetic or numeric character"));
}
if alias {
Ok(Token(start_mark, TokenType::Alias(string)))
} else {
Ok(Token(start_mark, TokenType::Anchor(string)))
}
}
fn fetch_flow_collection_start(&mut self, tok: TokenType) -> ScanResult {
// The indicators '[' and '{' may start a simple key.
self.save_simple_key()?;
self.increase_flow_level()?;
self.allow_simple_key();
let start_mark = self.mark;
self.skip();
if tok == TokenType::FlowMappingStart {
self.flow_mapping_started = true;
}
self.tokens.push_back(Token(start_mark, tok));
Ok(())
}
fn fetch_flow_collection_end(&mut self, tok: TokenType) -> ScanResult {
self.remove_simple_key()?;
self.decrease_flow_level();
self.disallow_simple_key();
self.end_implicit_mapping(self.mark);
let start_mark = self.mark;
self.skip();
self.tokens.push_back(Token(start_mark, tok));
Ok(())
}
/// Push the `FlowEntry` token and skip over the `,`.
fn fetch_flow_entry(&mut self) -> ScanResult {
self.remove_simple_key()?;
self.allow_simple_key();
self.end_implicit_mapping(self.mark);
let start_mark = self.mark;
self.skip();
self.tokens
.push_back(Token(start_mark, TokenType::FlowEntry));
Ok(())
}
fn increase_flow_level(&mut self) -> ScanResult {
self.simple_keys.push(SimpleKey::new(Marker::new(0, 0, 0)));
self.flow_level = self
.flow_level
.checked_add(1)
.ok_or_else(|| ScanError::new(self.mark, "recursion limit exceeded"))?;
Ok(())
}
fn decrease_flow_level(&mut self) {
if self.flow_level > 0 {
self.flow_level -= 1;
self.simple_keys.pop().unwrap();
}
}
/// Push the `Block*` token(s) and skip over the `-`.
///
/// Add an indentation level and push a `BlockSequenceStart` token if needed, then push a
/// `BlockEntry` token.
/// This function only skips over the `-` and does not fetch the entry value.
fn fetch_block_entry(&mut self) -> ScanResult {
if self.flow_level > 0 {
// - * only allowed in block
return Err(ScanError::new(
self.mark,
r#""-" is only valid inside a block"#,
));
}
// Check if we are allowed to start a new entry.
if !self.simple_key_allowed {
return Err(ScanError::new(
self.mark,
"block sequence entries are not allowed in this context",
));
}
// Skip over the `-`.
let mark = self.mark;
self.skip();
// generate BLOCK-SEQUENCE-START if indented
self.roll_indent(mark.col, None, TokenType::BlockSequenceStart, mark);
let found_tabs = self.skip_ws_to_eol(SkipTabs::Yes).found_tabs();
self.lookahead(2);
if found_tabs && self.buffer[0] == '-' && is_blankz(self.buffer[1]) {
return Err(ScanError::new(
self.mark,
"'-' must be followed by a valid YAML whitespace",
));
}
self.skip_ws_to_eol(SkipTabs::No);
if is_break(self.look_ch()) || is_flow(self.ch()) {
self.roll_one_col_indent();
}
self.remove_simple_key()?;
self.allow_simple_key();
self.tokens
.push_back(Token(self.mark, TokenType::BlockEntry));
Ok(())
}
fn fetch_document_indicator(&mut self, t: TokenType) -> ScanResult {
self.unroll_indent(-1);
self.remove_simple_key()?;
self.disallow_simple_key();
let mark = self.mark;
self.skip();
self.skip();
self.skip();
self.tokens.push_back(Token(mark, t));
Ok(())
}
fn fetch_block_scalar(&mut self, literal: bool) -> ScanResult {
self.save_simple_key()?;
self.allow_simple_key();
let tok = self.scan_block_scalar(literal)?;
self.tokens.push_back(tok);
Ok(())
}
#[allow(clippy::too_many_lines)]
fn scan_block_scalar(&mut self, literal: bool) -> Result<Token, ScanError> {
let start_mark = self.mark;
let mut chomping: i32 = 0;
let mut increment: usize = 0;
let mut indent: usize = 0;
let mut trailing_blank: bool;
let mut leading_blank: bool = false;
let mut string = String::new();
let mut leading_break = String::new();
let mut trailing_breaks = String::new();
// skip '|' or '>'
self.skip();
self.unroll_non_block_indents();
if self.look_ch() == '+' || self.ch() == '-' {
if self.ch() == '+' {
chomping = 1;
} else {
chomping = -1;
}
self.skip();
if is_digit(self.look_ch()) {
if self.ch() == '0' {
return Err(ScanError::new(
start_mark,
"while scanning a block scalar, found an indentation indicator equal to 0",
));
}
increment = (self.ch() as usize) - ('0' as usize);
self.skip();
}
} else if is_digit(self.ch()) {
if self.ch() == '0' {
return Err(ScanError::new(
start_mark,
"while scanning a block scalar, found an indentation indicator equal to 0",
));
}
increment = (self.ch() as usize) - ('0' as usize);
self.skip();
self.lookahead(1);
if self.ch() == '+' || self.ch() == '-' {
if self.ch() == '+' {
chomping = 1;
} else {
chomping = -1;
}
self.skip();
}
}
self.skip_ws_to_eol(SkipTabs::Yes);
// Check if we are at the end of the line.
if !is_breakz(self.ch()) {
return Err(ScanError::new(
start_mark,
"while scanning a block scalar, did not find expected comment or line break",
));
}
if is_break(self.ch()) {
self.lookahead(2);
self.skip_line();
}
if self.look_ch() == '\t' {
return Err(ScanError::new(
start_mark,
"a block scalar content cannot start with a tab",
));
}
if increment > 0 {
indent = if self.indent >= 0 {
(self.indent + increment as isize) as usize
} else {
increment
}
}
// Scan the leading line breaks and determine the indentation level if needed.
if indent == 0 {
self.skip_block_scalar_first_line_indent(&mut indent, &mut trailing_breaks);
} else {
self.skip_block_scalar_indent(indent, &mut trailing_breaks);
}
self.lookahead(1);
let start_mark = self.mark;
while self.mark.col == indent && !is_z(self.ch()) {
// We are at the beginning of a non-empty line.
trailing_blank = is_blank(self.ch());
if !literal && !leading_break.is_empty() && !leading_blank && !trailing_blank {
if trailing_breaks.is_empty() {
string.push(' ');
}
leading_break.clear();
} else {
string.push_str(&leading_break);
leading_break.clear();
}
string.push_str(&trailing_breaks);
trailing_breaks.clear();
leading_blank = is_blank(self.ch());
while !is_breakz(self.ch()) {
string.push(self.ch());
self.skip();
self.lookahead(1);
}
// break on EOF
if is_z(self.ch()) {
break;
}
self.lookahead(2);
self.read_break(&mut leading_break);
// Eat the following indentation spaces and line breaks.
self.skip_block_scalar_indent(indent, &mut trailing_breaks);
}
// Chomp the tail.
if chomping != -1 {
string.push_str(&leading_break);
}
if chomping == 1 {
string.push_str(&trailing_breaks);
}
if literal {
Ok(Token(
start_mark,
TokenType::Scalar(TScalarStyle::Literal, string),
))
} else {
Ok(Token(
start_mark,
TokenType::Scalar(TScalarStyle::Foled, string),
))
}
}
/// Skip the block scalar indentation and empty lines.
fn skip_block_scalar_indent(&mut self, indent: usize, breaks: &mut String) {
loop {
// Consume all spaces. Tabs cannot be used as indentation.
while self.mark.col < indent && self.look_ch() == ' ' {
self.skip();
}
// If our current line is empty, skip over the break and continue looping.
if is_break(self.look_ch()) {
self.lookahead(2);
self.read_break(breaks);
} else {
// Otherwise, we have a content line. Return control.
break;
}
}
}
/// Determine the indentation level for a block scalar from the first line of its contents.
///
/// The function skips over whitespace-only lines and sets `indent` to the the longest
/// whitespace line that was encountered.
fn skip_block_scalar_first_line_indent(&mut self, indent: &mut usize, breaks: &mut String) {
let mut max_indent = 0;
loop {
// Consume all spaces. Tabs cannot be used as indentation.
while self.look_ch() == ' ' {
self.skip();
}
if self.mark.col > max_indent {
max_indent = self.mark.col;
}
if is_break(self.look_ch()) {
// If our current line is empty, skip over the break and continue looping.
self.lookahead(2);
self.read_break(breaks);
} else {
// Otherwise, we have a content line. Return control.
break;
}
}
*indent = max_indent.max((self.indent + 1) as usize).max(1);
}
fn fetch_flow_scalar(&mut self, single: bool) -> ScanResult {
self.save_simple_key()?;
self.disallow_simple_key();
let tok = self.scan_flow_scalar(single)?;
// From spec: To ensure JSON compatibility, if a key inside a flow mapping is JSON-like,
// YAML allows the following value to be specified adjacent to the “:”.
self.adjacent_value_allowed_at = self.mark.index;
self.tokens.push_back(tok);
Ok(())
}
#[allow(clippy::too_many_lines)]
fn scan_flow_scalar(&mut self, single: bool) -> Result<Token, ScanError> {
let start_mark = self.mark;
let mut string = String::new();
let mut leading_break = String::new();
let mut trailing_breaks = String::new();
let mut whitespaces = String::new();
let mut leading_blanks;
/* Eat the left quote. */
self.skip();
loop {
/* Check for a document indicator. */
self.lookahead(4);
if self.mark.col == 0
&& (((self.buffer[0] == '-') && (self.buffer[1] == '-') && (self.buffer[2] == '-'))
|| ((self.buffer[0] == '.')
&& (self.buffer[1] == '.')
&& (self.buffer[2] == '.')))
&& is_blankz(self.buffer[3])
{
return Err(ScanError::new(
start_mark,
"while scanning a quoted scalar, found unexpected document indicator",
));
}
if is_z(self.ch()) {
return Err(ScanError::new(
start_mark,
"while scanning a quoted scalar, found unexpected end of stream",
));
}
self.lookahead(2);
leading_blanks = false;
// Consume non-blank characters.
while !is_blankz(self.ch()) {
match self.ch() {
// Check for an escaped single quote.
'\'' if self.buffer[1] == '\'' && single => {
string.push('\'');
self.skip();
self.skip();
}
// Check for the right quote.
'\'' if single => break,
'"' if !single => break,
// Check for an escaped line break.
'\\' if !single && is_break(self.buffer[1]) => {
self.lookahead(3);
self.skip();
self.skip_line();
leading_blanks = true;
break;
}
// Check for an escape sequence.
'\\' if !single => {
let mut code_length = 0usize;
match self.buffer[1] {
'0' => string.push('\0'),
'a' => string.push('\x07'),
'b' => string.push('\x08'),
't' | '\t' => string.push('\t'),
'n' => string.push('\n'),
'v' => string.push('\x0b'),
'f' => string.push('\x0c'),
'r' => string.push('\x0d'),
'e' => string.push('\x1b'),
' ' => string.push('\x20'),
'"' => string.push('"'),
'\'' => string.push('\''),
'\\' => string.push('\\'),
// NEL (#x85)
'N' => string.push(char::from_u32(0x85).unwrap()),
// #xA0
'_' => string.push(char::from_u32(0xA0).unwrap()),
// LS (#x2028)
'L' => string.push(char::from_u32(0x2028).unwrap()),
// PS (#x2029)
'P' => string.push(char::from_u32(0x2029).unwrap()),
'x' => code_length = 2,
'u' => code_length = 4,
'U' => code_length = 8,
_ => {
return Err(ScanError::new(
start_mark,
"while parsing a quoted scalar, found unknown escape character",
))
}
}
self.skip();
self.skip();
// Consume an arbitrary escape code.
if code_length > 0 {
self.lookahead(code_length);
let mut value = 0u32;
for i in 0..code_length {
if !is_hex(self.buffer[i]) {
return Err(ScanError::new(start_mark,
"while parsing a quoted scalar, did not find expected hexadecimal number"));
}
value = (value << 4) + as_hex(self.buffer[i]);
}
let Some(ch) = char::from_u32(value) else {
return Err(ScanError::new(start_mark, "while parsing a quoted scalar, found invalid Unicode character escape code"));
};
string.push(ch);
for _ in 0..code_length {
self.skip();
}
}
}
c => {
string.push(c);
self.skip();
}
}
self.lookahead(2);
}
self.lookahead(1);
match self.ch() {
'\'' if single => break,
'"' if !single => break,
_ => {}
}
// Consume blank characters.
while is_blank(self.ch()) || is_break(self.ch()) {
if is_blank(self.ch()) {
// Consume a space or a tab character.
if leading_blanks {
if self.ch() == '\t' && (self.mark.col as isize) < self.indent {
return Err(ScanError::new(
self.mark,
"tab cannot be used as indentation",
));
}
self.skip();
} else {
whitespaces.push(self.ch());
self.skip();
}
} else {
self.lookahead(2);
// Check if it is a first line break.
if leading_blanks {
self.read_break(&mut trailing_breaks);
} else {
whitespaces.clear();
self.read_break(&mut leading_break);
leading_blanks = true;
}
}
self.lookahead(1);
}
// Join the whitespaces or fold line breaks.
if leading_blanks {
if leading_break.is_empty() {
string.push_str(&leading_break);
string.push_str(&trailing_breaks);
trailing_breaks.clear();
leading_break.clear();
} else {
if trailing_breaks.is_empty() {
string.push(' ');
} else {
string.push_str(&trailing_breaks);
trailing_breaks.clear();
}
leading_break.clear();
}
} else {
string.push_str(&whitespaces);
whitespaces.clear();
}
} // loop
// Eat the right quote.
self.skip();
if single {
Ok(Token(
start_mark,
TokenType::Scalar(TScalarStyle::SingleQuoted, string),
))
} else {
Ok(Token(
start_mark,
TokenType::Scalar(TScalarStyle::DoubleQuoted, string),
))
}
}
fn fetch_plain_scalar(&mut self) -> ScanResult {
self.save_simple_key()?;
self.disallow_simple_key();
let tok = self.scan_plain_scalar()?;
self.tokens.push_back(tok);
Ok(())
}
fn scan_plain_scalar(&mut self) -> Result<Token, ScanError> {
self.unroll_non_block_indents();
let indent = self.indent + 1;
let start_mark = self.mark;
let mut string = String::new();
let mut leading_break = String::new();
let mut trailing_breaks = String::new();
let mut whitespaces = String::new();
let mut leading_blanks = true;
loop {
/* Check for a document indicator. */
self.lookahead(4);
if self.mark.col == 0
&& (((self.buffer[0] == '-') && (self.buffer[1] == '-') && (self.buffer[2] == '-'))
|| ((self.buffer[0] == '.')
&& (self.buffer[1] == '.')
&& (self.buffer[2] == '.')))
&& is_blankz(self.buffer[3])
{
break;
}
if self.ch() == '#' {
break;
}
while !is_blankz(self.ch()) {
// indicators can end a plain scalar, see 7.3.3. Plain Style
match self.ch() {
':' if is_blankz(self.buffer[1])
|| (self.flow_level > 0 && is_flow(self.buffer[1])) =>
{
break;
}
',' | '[' | ']' | '{' | '}' if self.flow_level > 0 => break,
_ => {}
}
if leading_blanks || !whitespaces.is_empty() {
if leading_blanks {
if leading_break.is_empty() {
string.push_str(&leading_break);
string.push_str(&trailing_breaks);
trailing_breaks.clear();
leading_break.clear();
} else {
if trailing_breaks.is_empty() {
string.push(' ');
} else {
string.push_str(&trailing_breaks);
trailing_breaks.clear();
}
leading_break.clear();
}
leading_blanks = false;
} else {
string.push_str(&whitespaces);
whitespaces.clear();
}
}
string.push(self.ch());
self.skip();
self.lookahead(2);
}
// is the end?
if !(is_blank(self.ch()) || is_break(self.ch())) {
break;
}
while is_blank(self.look_ch()) || is_break(self.ch()) {
if is_blank(self.ch()) {
if leading_blanks && (self.mark.col as isize) < indent && self.ch() == '\t' {
// If our line contains only whitespace, this is not an error.
// Skip over it.
self.skip_ws_to_eol(SkipTabs::Yes);
if is_breakz(self.ch()) {
continue;
}
return Err(ScanError::new(
start_mark,
"while scanning a plain scalar, found a tab",
));
}
if !leading_blanks {
whitespaces.push(self.ch());
}
self.skip();
} else {
self.lookahead(2);
// Check if it is a first line break
if leading_blanks {
self.read_break(&mut trailing_breaks);
} else {
whitespaces.clear();
self.read_break(&mut leading_break);
leading_blanks = true;
}
}
}
// check indentation level
if self.flow_level == 0 && (self.mark.col as isize) < indent {
break;
}
}
if leading_blanks {
self.allow_simple_key();
}
Ok(Token(
start_mark,
TokenType::Scalar(TScalarStyle::Plain, string),
))
}
fn fetch_key(&mut self) -> ScanResult {
let start_mark = self.mark;
if self.flow_level == 0 {
// Check if we are allowed to start a new key (not necessarily simple).
if !self.simple_key_allowed {
return Err(ScanError::new(
self.mark,
"mapping keys are not allowed in this context",
));
}
self.roll_indent(
start_mark.col,
None,
TokenType::BlockMappingStart,
start_mark,
);
} else {
// The parser, upon receiving a `Key`, will insert a `MappingStart` event.
self.flow_mapping_started = true;
}
self.remove_simple_key()?;
if self.flow_level == 0 {
self.allow_simple_key();
} else {
self.disallow_simple_key();
}
self.skip();
self.skip_yaml_whitespace()?;
if self.ch() == '\t' {
return Err(ScanError::new(
self.mark(),
"tabs disallowed in this context",
));
}
self.tokens.push_back(Token(start_mark, TokenType::Key));
Ok(())
}
/// Fetch a value from a mapping (after a `:`).
fn fetch_value(&mut self) -> ScanResult {
let sk = self.simple_keys.last().unwrap().clone();
let start_mark = self.mark;
self.implicit_flow_mapping = self.flow_level > 0 && !self.flow_mapping_started;
// Skip over ':'.
self.skip();
if self.look_ch() == '\t'
&& !self.skip_ws_to_eol(SkipTabs::Yes).has_valid_yaml_ws()
&& (self.ch() == '-' || is_alpha(self.ch()))
{
return Err(ScanError::new(
self.mark,
"':' must be followed by a valid YAML whitespace",
));
}
if sk.possible {
// insert simple key
let tok = Token(sk.mark, TokenType::Key);
let tokens_parsed = self.tokens_parsed;
self.insert_token(sk.token_number - tokens_parsed, tok);
if self.implicit_flow_mapping {
self.insert_token(
sk.token_number - tokens_parsed,
Token(self.mark, TokenType::FlowMappingStart),
);
}
// Add the BLOCK-MAPPING-START token if needed.
self.roll_indent(
sk.mark.col,
Some(sk.token_number),
TokenType::BlockMappingStart,
start_mark,
);
self.roll_one_col_indent();
self.simple_keys.last_mut().unwrap().possible = false;
self.disallow_simple_key();
} else {
if self.implicit_flow_mapping {
self.tokens
.push_back(Token(self.mark, TokenType::FlowMappingStart));
}
// The ':' indicator follows a complex key.
if self.flow_level == 0 {
if !self.simple_key_allowed {
return Err(ScanError::new(
start_mark,
"mapping values are not allowed in this context",
));
}
self.roll_indent(
start_mark.col,
None,
TokenType::BlockMappingStart,
start_mark,
);
}
self.roll_one_col_indent();
if self.flow_level == 0 {
self.allow_simple_key();
} else {
self.disallow_simple_key();
}
}
self.tokens.push_back(Token(start_mark, TokenType::Value));
Ok(())
}
/// Add an indentation level to the stack with the given block token, if needed.
///
/// An indentation level is added only if:
/// - We are not in a flow-style construct (which don't have indentation per-se).
/// - The current column is further indented than the last indent we have registered.
fn roll_indent(&mut self, col: usize, number: Option<usize>, tok: TokenType, mark: Marker) {
if self.flow_level > 0 {
return;
}
// If the last indent was a non-block indent, remove it.
// This means that we prepared an indent that we thought we wouldn't use, but realized just
// now that it is a block indent.
if self.indent <= col as isize {
if let Some(indent) = self.indents.last() {
if !indent.needs_block_end {
self.indent = indent.indent;
self.indents.pop();
}
}
}
if self.indent < col as isize {
self.indents.push(Indent {
indent: self.indent,
needs_block_end: true,
});
self.indent = col as isize;
let tokens_parsed = self.tokens_parsed;
match number {
Some(n) => self.insert_token(n - tokens_parsed, Token(mark, tok)),
None => self.tokens.push_back(Token(mark, tok)),
}
}
}
/// Pop indentation levels from the stack as much as needed.
///
/// Indentation levels are popped from the stack while they are further indented than `col`.
/// If we are in a flow-style construct (which don't have indentation per-se), this function
/// does nothing.
fn unroll_indent(&mut self, col: isize) {
if self.flow_level > 0 {
return;
}
while self.indent > col {
let indent = self.indents.pop().unwrap();
self.indent = indent.indent;
if indent.needs_block_end {
self.tokens.push_back(Token(self.mark, TokenType::BlockEnd));
}
}
}
/// Add an indentation level of 1 column that does not start a block.
///
/// See the documentation of [`Indent::needs_block_end`] for more details.
fn roll_one_col_indent(&mut self) {
if self.flow_level == 0 {
self.indents.push(Indent {
indent: self.indent,
needs_block_end: false,
});
self.indent += 1;
}
}
/// Unroll all last indents created with [`Self::roll_one_col_indent`].
fn unroll_non_block_indents(&mut self) {
while let Some(indent) = self.indents.last() {
if indent.needs_block_end {
break;
} else {
self.indent = indent.indent;
self.indents.pop();
}
}
}
fn save_simple_key(&mut self) -> ScanResult {
if self.simple_key_allowed {
let required = self.flow_level > 0
&& self.indent == (self.mark.col as isize)
&& self.indents.last().unwrap().needs_block_end;
let mut sk = SimpleKey::new(self.mark);
sk.possible = true;
sk.required = required;
sk.token_number = self.tokens_parsed + self.tokens.len();
self.remove_simple_key()?;
self.simple_keys.pop();
self.simple_keys.push(sk);
}
Ok(())
}
fn remove_simple_key(&mut self) -> ScanResult {
let last = self.simple_keys.last_mut().unwrap();
if last.possible && last.required {
return Err(ScanError::new(self.mark, "simple key expected"));
}
last.possible = false;
Ok(())
}
/// Return whether the scanner is inside a block but outside of a flow sequence.
fn is_within_block(&self) -> bool {
!self.indents.is_empty()
}
/// If an implicit mapping had started, end it.
fn end_implicit_mapping(&mut self, mark: Marker) {
if self.implicit_flow_mapping {
self.implicit_flow_mapping = false;
self.flow_mapping_started = false;
self.tokens
.push_back(Token(mark, TokenType::FlowMappingEnd));
}
}
}
/// Behavior to adopt regarding treating tabs as whitespace.
///
/// Although tab is a valid yaml whitespace, it doesn't always behave the same as a space.
#[derive(Copy, Clone, Eq, PartialEq)]
enum SkipTabs {
/// Skip all tabs as whitespace.
Yes,
/// Don't skip any tab. Return from the function when encountering one.
No,
/// Return value from the function.
Result(
/// Whether tabs were encountered.
bool,
/// Whether at least 1 valid yaml whitespace has been encountered.
bool,
),
}
impl SkipTabs {
/// Whether tabs were found while skipping whitespace.
///
/// This function must be called after a call to `skip_ws_to_eol`.
fn found_tabs(self) -> bool {
matches!(self, SkipTabs::Result(true, _))
}
/// Whether a valid YAML whitespace has been found in skipped-over content.
///
/// This function must be called after a call to `skip_ws_to_eol`.
fn has_valid_yaml_ws(self) -> bool {
matches!(self, SkipTabs::Result(_, true))
}
}
#[cfg(test)]
mod test {
#[test]
fn test_is_anchor_char() {
use super::is_anchor_char;
assert!(is_anchor_char('x'));
}
}