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Extract pull parser.

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This commit is contained in:
Christian Hofer 2017-06-22 08:44:46 +02:00
parent 92809b3f8a
commit b2f0df8e00
1 changed files with 97 additions and 53 deletions
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150
saphyr/src/parser.rs
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@ -1,8 +1,5 @@
use scanner::*; use scanner::*;
use std::collections::HashMap; use std::collections::HashMap;
use std::mem::swap;
// use yaml::*;
#[derive(Clone, Copy, PartialEq, Debug, Eq)] #[derive(Clone, Copy, PartialEq, Debug, Eq)]
enum State { enum State {
@ -72,6 +69,7 @@ pub struct Parser<T> {
state: State, state: State,
marks: Vec<Marker>, marks: Vec<Marker>,
token: Option<Token>, token: Option<Token>,
current: Option<(Event, Marker)>,
anchors: HashMap<String, usize>, anchors: HashMap<String, usize>,
anchor_id: usize, anchor_id: usize,
} }
@ -102,6 +100,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
state: State::StreamStart, state: State::StreamStart,
marks: Vec::new(), marks: Vec::new(),
token: None, token: None,
current: None,
anchors: HashMap::new(), anchors: HashMap::new(),
// valid anchor_id starts from 1 // valid anchor_id starts from 1
@ -109,7 +108,26 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
} }
fn peek(&mut self) -> Result<&Token, ScanError> { pub fn peek(&mut self) -> Result<&(Event, Marker), ScanError> {
match self.current {
Some(ref x) => Ok(x),
None => {
self.current = Some(self.next()?);
self.peek()
}
}
}
pub fn next(&mut self) -> ParseResult {
match self.current {
None => self.parse(),
Some(_) => {
Ok(self.current.take().unwrap())
}
}
}
fn peek_token(&mut self) -> Result<&Token, ScanError> {
match self.token { match self.token {
None => { None => {
self.token = Some(try!(self.scan_next_token())); self.token = Some(try!(self.scan_next_token()));
@ -132,15 +150,13 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
fn fetch_token(&mut self) -> Token { fn fetch_token(&mut self) -> Token {
let mut token = None; self.token.take().expect("fetch_token needs to be preceded by peek_token")
swap(&mut token, &mut self.token);
token.expect("fetch_token needs to be preceded by peek")
} }
fn skip(&mut self) { fn skip(&mut self) {
self.token = None; self.token = None;
//self.peek(); //self.peek_token();
} }
fn pop_state(&mut self) { fn pop_state(&mut self) {
self.state = self.states.pop().unwrap() self.state = self.states.pop().unwrap()
@ -161,7 +177,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
pub fn load<R: MarkedEventReceiver>(&mut self, recv: &mut R, multi: bool) pub fn load<R: MarkedEventReceiver>(&mut self, recv: &mut R, multi: bool)
-> Result<(), ScanError> { -> Result<(), ScanError> {
if !self.scanner.stream_started() { if !self.scanner.stream_started() {
let (ev, mark) = try!(self.parse()); let (ev, mark) = try!(self.next());
assert_eq!(ev, Event::StreamStart); assert_eq!(ev, Event::StreamStart);
recv.on_event(ev, mark); recv.on_event(ev, mark);
} }
@ -172,7 +188,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
return Ok(()); return Ok(());
} }
loop { loop {
let (ev, mark) = try!(self.parse()); let (ev, mark) = try!(self.next());
if ev == Event::StreamEnd { if ev == Event::StreamEnd {
recv.on_event(ev, mark); recv.on_event(ev, mark);
return Ok(()); return Ok(());
@ -192,11 +208,11 @@ impl<T: Iterator<Item=char>> Parser<T> {
assert_eq!(first_ev, Event::DocumentStart); assert_eq!(first_ev, Event::DocumentStart);
recv.on_event(first_ev, mark); recv.on_event(first_ev, mark);
let (ev, mark) = try!(self.parse()); let (ev, mark) = try!(self.next());
try!(self.load_node(ev, mark, recv)); try!(self.load_node(ev, mark, recv));
// DOCUMENT-END is expected. // DOCUMENT-END is expected.
let (ev, mark) = try!(self.parse()); let (ev, mark) = try!(self.next());
assert_eq!(ev, Event::DocumentEnd); assert_eq!(ev, Event::DocumentEnd);
recv.on_event(ev, mark); recv.on_event(ev, mark);
@ -225,17 +241,17 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn load_mapping<R: MarkedEventReceiver>(&mut self, recv: &mut R) fn load_mapping<R: MarkedEventReceiver>(&mut self, recv: &mut R)
-> Result<(), ScanError> { -> Result<(), ScanError> {
let (mut key_ev, mut key_mark) = try!(self.parse()); let (mut key_ev, mut key_mark) = try!(self.next());
while key_ev != Event::MappingEnd { while key_ev != Event::MappingEnd {
// key // key
try!(self.load_node(key_ev, key_mark, recv)); try!(self.load_node(key_ev, key_mark, recv));
// value // value
let (ev, mark) = try!(self.parse()); let (ev, mark) = try!(self.next());
try!(self.load_node(ev, mark, recv)); try!(self.load_node(ev, mark, recv));
// next event // next event
let (ev, mark) = try!(self.parse()); let (ev, mark) = try!(self.next());
key_ev = ev; key_ev = ev;
key_mark = mark; key_mark = mark;
@ -246,12 +262,12 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn load_sequence<R: MarkedEventReceiver>(&mut self, recv: &mut R) fn load_sequence<R: MarkedEventReceiver>(&mut self, recv: &mut R)
-> Result<(), ScanError> { -> Result<(), ScanError> {
let (mut ev, mut mark) = try!(self.parse()); let (mut ev, mut mark) = try!(self.next());
while ev != Event::SequenceEnd { while ev != Event::SequenceEnd {
try!(self.load_node(ev, mark, recv)); try!(self.load_node(ev, mark, recv));
// next event // next event
let (next_ev, next_mark) = try!(self.parse()); let (next_ev, next_mark) = try!(self.next());
ev = next_ev; ev = next_ev;
mark = next_mark; mark = next_mark;
} }
@ -260,7 +276,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
fn state_machine(&mut self) -> ParseResult { fn state_machine(&mut self) -> ParseResult {
// let next_tok = try!(self.peek()); // let next_tok = try!(self.peek_token());
// println!("cur_state {:?}, next tok: {:?}", self.state, next_tok); // println!("cur_state {:?}, next tok: {:?}", self.state, next_tok);
match self.state { match self.state {
State::StreamStart => self.stream_start(), State::StreamStart => self.stream_start(),
@ -301,7 +317,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
fn stream_start(&mut self) -> ParseResult { fn stream_start(&mut self) -> ParseResult {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::StreamStart(_)) => { Token(mark, TokenType::StreamStart(_)) => {
self.state = State::ImplicitDocumentStart; self.state = State::ImplicitDocumentStart;
self.skip(); self.skip();
@ -314,12 +330,12 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn document_start(&mut self, implicit: bool) -> ParseResult { fn document_start(&mut self, implicit: bool) -> ParseResult {
if !implicit { if !implicit {
while let TokenType::DocumentEnd = try!(self.peek()).1 { while let TokenType::DocumentEnd = try!(self.peek_token()).1 {
self.skip(); self.skip();
} }
} }
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::StreamEnd) => { Token(mark, TokenType::StreamEnd) => {
self.state = State::End; self.state = State::End;
self.skip(); self.skip();
@ -346,7 +362,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn parser_process_directives(&mut self) -> Result<(), ScanError> { fn parser_process_directives(&mut self) -> Result<(), ScanError> {
loop { loop {
match try!(self.peek()).1 { match try!(self.peek_token()).1 {
TokenType::VersionDirective(_, _) => { TokenType::VersionDirective(_, _) => {
// XXX parsing with warning according to spec // XXX parsing with warning according to spec
//if major != 1 || minor > 2 { //if major != 1 || minor > 2 {
@ -367,7 +383,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn _explict_document_start(&mut self) -> ParseResult { fn _explict_document_start(&mut self) -> ParseResult {
try!(self.parser_process_directives()); try!(self.parser_process_directives());
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::DocumentStart) => { Token(mark, TokenType::DocumentStart) => {
self.push_state(State::DocumentEnd); self.push_state(State::DocumentEnd);
self.state = State::DocumentContent; self.state = State::DocumentContent;
@ -379,7 +395,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
fn document_content(&mut self) -> ParseResult { fn document_content(&mut self) -> ParseResult {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::VersionDirective(..)) Token(mark, TokenType::VersionDirective(..))
| Token(mark, TokenType::TagDirective(..)) | Token(mark, TokenType::TagDirective(..))
| Token(mark, TokenType::DocumentStart) | Token(mark, TokenType::DocumentStart)
@ -397,7 +413,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn document_end(&mut self) -> ParseResult { fn document_end(&mut self) -> ParseResult {
let mut _implicit = true; let mut _implicit = true;
let marker: Marker = match *try!(self.peek()) { let marker: Marker = match *try!(self.peek_token()) {
Token(mark, TokenType::DocumentEnd) => { Token(mark, TokenType::DocumentEnd) => {
self.skip(); self.skip();
_implicit = false; _implicit = false;
@ -426,7 +442,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn parse_node(&mut self, block: bool, indentless_sequence: bool) -> ParseResult { fn parse_node(&mut self, block: bool, indentless_sequence: bool) -> ParseResult {
let mut anchor_id = 0; let mut anchor_id = 0;
let mut tag = None; let mut tag = None;
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(_, TokenType::Alias(_)) => { Token(_, TokenType::Alias(_)) => {
self.pop_state(); self.pop_state();
if let Token(mark, TokenType::Alias(name)) = self.fetch_token() { if let Token(mark, TokenType::Alias(name)) = self.fetch_token() {
@ -441,7 +457,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
Token(_, TokenType::Anchor(_)) => { Token(_, TokenType::Anchor(_)) => {
if let Token(mark, TokenType::Anchor(name)) = self.fetch_token() { if let Token(mark, TokenType::Anchor(name)) = self.fetch_token() {
anchor_id = try!(self.register_anchor(name, &mark)); anchor_id = try!(self.register_anchor(name, &mark));
if let TokenType::Tag(..) = try!(self.peek()).1 { if let TokenType::Tag(..) = try!(self.peek_token()).1 {
if let tg @ TokenType::Tag(..) = self.fetch_token().1 { if let tg @ TokenType::Tag(..) = self.fetch_token().1 {
tag = Some(tg); tag = Some(tg);
} else { } else {
@ -455,7 +471,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
Token(_, TokenType::Tag(..)) => { Token(_, TokenType::Tag(..)) => {
if let tg @ TokenType::Tag(..) = self.fetch_token().1 { if let tg @ TokenType::Tag(..) = self.fetch_token().1 {
tag = Some(tg); tag = Some(tg);
if let TokenType::Anchor(_) = try!(self.peek()).1 { if let TokenType::Anchor(_) = try!(self.peek_token()).1 {
if let Token(mark, TokenType::Anchor(name)) = self.fetch_token() { if let Token(mark, TokenType::Anchor(name)) = self.fetch_token() {
anchor_id = try!(self.register_anchor(name, &mark)); anchor_id = try!(self.register_anchor(name, &mark));
} else { } else {
@ -468,7 +484,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
}, },
_ => {} _ => {}
} }
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::BlockEntry) if indentless_sequence => { Token(mark, TokenType::BlockEntry) if indentless_sequence => {
self.state = State::IndentlessSequenceEntry; self.state = State::IndentlessSequenceEntry;
Ok((Event::SequenceStart(anchor_id), mark)) Ok((Event::SequenceStart(anchor_id), mark))
@ -509,14 +525,14 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn block_mapping_key(&mut self, first: bool) -> ParseResult { fn block_mapping_key(&mut self, first: bool) -> ParseResult {
// skip BlockMappingStart // skip BlockMappingStart
if first { if first {
let _ = try!(self.peek()); let _ = try!(self.peek_token());
//self.marks.push(tok.0); //self.marks.push(tok.0);
self.skip(); self.skip();
} }
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(_, TokenType::Key) => { Token(_, TokenType::Key) => {
self.skip(); self.skip();
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::Key) Token(mark, TokenType::Key)
| Token(mark, TokenType::Value) | Token(mark, TokenType::Value)
| Token(mark, TokenType::BlockEnd) => { | Token(mark, TokenType::BlockEnd) => {
@ -547,10 +563,10 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
fn block_mapping_value(&mut self) -> ParseResult { fn block_mapping_value(&mut self) -> ParseResult {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(_, TokenType::Value) => { Token(_, TokenType::Value) => {
self.skip(); self.skip();
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::Key) Token(mark, TokenType::Key)
| Token(mark, TokenType::Value) | Token(mark, TokenType::Value)
| Token(mark, TokenType::BlockEnd) => { | Token(mark, TokenType::BlockEnd) => {
@ -574,25 +590,25 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn flow_mapping_key(&mut self, first: bool) -> ParseResult { fn flow_mapping_key(&mut self, first: bool) -> ParseResult {
if first { if first {
let _ = try!(self.peek()); let _ = try!(self.peek_token());
self.skip(); self.skip();
} }
let marker: Marker = { let marker: Marker = {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::FlowMappingEnd) => mark, Token(mark, TokenType::FlowMappingEnd) => mark,
Token(mark, _) => { Token(mark, _) => {
if !first { if !first {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(_, TokenType::FlowEntry) => self.skip(), Token(_, TokenType::FlowEntry) => self.skip(),
Token(mark, _) => return Err(ScanError::new(mark, Token(mark, _) => return Err(ScanError::new(mark,
"while parsing a flow mapping, did not find expected ',' or '}'")) "while parsing a flow mapping, did not find expected ',' or '}'"))
} }
} }
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(_, TokenType::Key) => { Token(_, TokenType::Key) => {
self.skip(); self.skip();
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::Value) Token(mark, TokenType::Value)
| Token(mark, TokenType::FlowEntry) | Token(mark, TokenType::FlowEntry)
| Token(mark, TokenType::FlowMappingEnd) => { | Token(mark, TokenType::FlowMappingEnd) => {
@ -629,14 +645,14 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn flow_mapping_value(&mut self, empty: bool) -> ParseResult { fn flow_mapping_value(&mut self, empty: bool) -> ParseResult {
let mark: Marker = { let mark: Marker = {
if empty { if empty {
let Token(mark, _) = *try!(self.peek()); let Token(mark, _) = *try!(self.peek_token());
self.state = State::FlowMappingKey; self.state = State::FlowMappingKey;
return Ok((Event::empty_scalar(), mark)); return Ok((Event::empty_scalar(), mark));
} else { } else {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(marker, TokenType::Value) => { Token(marker, TokenType::Value) => {
self.skip(); self.skip();
match try!(self.peek()).1 { match try!(self.peek_token()).1 {
TokenType::FlowEntry TokenType::FlowEntry
| TokenType::FlowMappingEnd => { }, | TokenType::FlowMappingEnd => { },
_ => { _ => {
@ -658,11 +674,11 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn flow_sequence_entry(&mut self, first: bool) -> ParseResult { fn flow_sequence_entry(&mut self, first: bool) -> ParseResult {
// skip FlowMappingStart // skip FlowMappingStart
if first { if first {
let _ = try!(self.peek()); let _ = try!(self.peek_token());
//self.marks.push(tok.0); //self.marks.push(tok.0);
self.skip(); self.skip();
} }
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::FlowSequenceEnd) => { Token(mark, TokenType::FlowSequenceEnd) => {
self.pop_state(); self.pop_state();
self.skip(); self.skip();
@ -677,7 +693,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
_ => { /* next */ } _ => { /* next */ }
} }
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::FlowSequenceEnd) => { Token(mark, TokenType::FlowSequenceEnd) => {
self.pop_state(); self.pop_state();
self.skip(); self.skip();
@ -696,7 +712,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
fn indentless_sequence_entry(&mut self) -> ParseResult { fn indentless_sequence_entry(&mut self) -> ParseResult {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(_, TokenType::BlockEntry) => (), Token(_, TokenType::BlockEntry) => (),
Token(mark, _) => { Token(mark, _) => {
self.pop_state(); self.pop_state();
@ -704,7 +720,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
} }
self.skip(); self.skip();
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::BlockEntry) Token(mark, TokenType::BlockEntry)
| Token(mark, TokenType::Key) | Token(mark, TokenType::Key)
| Token(mark, TokenType::Value) | Token(mark, TokenType::Value)
@ -722,11 +738,11 @@ impl<T: Iterator<Item=char>> Parser<T> {
fn block_sequence_entry(&mut self, first: bool) -> ParseResult { fn block_sequence_entry(&mut self, first: bool) -> ParseResult {
// BLOCK-SEQUENCE-START // BLOCK-SEQUENCE-START
if first { if first {
let _ = try!(self.peek()); let _ = try!(self.peek_token());
//self.marks.push(tok.0); //self.marks.push(tok.0);
self.skip(); self.skip();
} }
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::BlockEnd) => { Token(mark, TokenType::BlockEnd) => {
self.pop_state(); self.pop_state();
self.skip(); self.skip();
@ -734,7 +750,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
}, },
Token(_, TokenType::BlockEntry) => { Token(_, TokenType::BlockEntry) => {
self.skip(); self.skip();
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::BlockEntry) Token(mark, TokenType::BlockEntry)
| Token(mark, TokenType::BlockEnd) => { | Token(mark, TokenType::BlockEnd) => {
self.state = State::BlockSequenceEntry; self.state = State::BlockSequenceEntry;
@ -754,7 +770,7 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
fn flow_sequence_entry_mapping_key(&mut self) -> ParseResult { fn flow_sequence_entry_mapping_key(&mut self) -> ParseResult {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::Value) Token(mark, TokenType::Value)
| Token(mark, TokenType::FlowEntry) | Token(mark, TokenType::FlowEntry)
| Token(mark, TokenType::FlowSequenceEnd) => { | Token(mark, TokenType::FlowSequenceEnd) => {
@ -770,11 +786,11 @@ impl<T: Iterator<Item=char>> Parser<T> {
} }
fn flow_sequence_entry_mapping_value(&mut self) -> ParseResult { fn flow_sequence_entry_mapping_value(&mut self) -> ParseResult {
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(_, TokenType::Value) => { Token(_, TokenType::Value) => {
self.skip(); self.skip();
self.state = State::FlowSequenceEntryMappingValue; self.state = State::FlowSequenceEntryMappingValue;
match *try!(self.peek()) { match *try!(self.peek_token()) {
Token(mark, TokenType::FlowEntry) Token(mark, TokenType::FlowEntry)
| Token(mark, TokenType::FlowSequenceEnd) => { | Token(mark, TokenType::FlowSequenceEnd) => {
self.state = State::FlowSequenceEntryMappingEnd; self.state = State::FlowSequenceEntryMappingEnd;
@ -798,3 +814,31 @@ impl<T: Iterator<Item=char>> Parser<T> {
Ok((Event::MappingEnd, self.scanner.mark())) Ok((Event::MappingEnd, self.scanner.mark()))
} }
} }
#[cfg(test)]
mod test {
use super::{Event, Parser};
#[test]
fn test_peek_eq_parse() {
let s = "
a0 bb: val
a1: &x
b1: 4
b2: d
a2: 4
a3: [1, 2, 3]
a4:
- [a1, a2]
- 2
a5: *x
";
let mut p = Parser::new(s.chars());
while {
let event_peek = p.peek().unwrap().clone();
let event = p.next().unwrap();
assert_eq!(event, event_peek);
event.0 != Event::StreamEnd
} {}
}
}