From edc686d7384470068858e16f2926cf50f31b2c90 Mon Sep 17 00:00:00 2001 From: Martin Haug Date: Sat, 27 Nov 2021 16:10:22 +0100 Subject: Make incremental parsing simpler and move it somewhere else --- src/parse/incremental.rs | 661 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 661 insertions(+) create mode 100644 src/parse/incremental.rs (limited to 'src/parse/incremental.rs') diff --git a/src/parse/incremental.rs b/src/parse/incremental.rs new file mode 100644 index 00000000..9c912aae --- /dev/null +++ b/src/parse/incremental.rs @@ -0,0 +1,661 @@ +use std::ops::Range; +use std::rc::Rc; + +use crate::syntax::{Green, GreenNode, NodeKind, Span}; + +use super::{ + parse_atomic, parse_atomic_markup, parse_block, parse_comment, parse_markup, + parse_markup_elements, parse_template, TokenMode, +}; + +/// Allows partial refreshs of the [`Green`] node tree. +/// +/// This struct holds a description of a change. Its methods can be used to try +/// and apply the change to a green tree. +pub struct Reparser<'a> { + /// The new source code, with the change applied. + src: &'a str, + /// Which range in the old source file was changed. + replace_range: Span, + /// How many characters replaced the text in `replacement_range`. + replace_len: usize, +} + +impl<'a> Reparser<'a> { + /// Create a new reparser. + pub fn new(src: &'a str, replace_range: Span, replace_len: usize) -> Self { + Self { src, replace_range, replace_len } + } +} + +impl Reparser<'_> { + /// Find the innermost child that is incremental safe. + pub fn reparse(&self, green: &mut GreenNode) -> Result, ()> { + self.reparse_step(green, 0, TokenMode::Markup, true) + } + + fn reparse_step( + &self, + green: &mut GreenNode, + mut offset: usize, + parent_mode: TokenMode, + outermost: bool, + ) -> Result, ()> { + let kind = green.kind().clone(); + let mode = kind.mode().unwrap_or(parent_mode); + + let mut loop_result = None; + let mut child_at_start = true; + let last = green.children().len() - 1; + let mut start = None; + + for (i, child) in green.children_mut().iter_mut().enumerate() { + let child_span = + Span::new(self.replace_range.source, offset, offset + child.len()); + + // We look for the start in the element but we only take a position + // at the right border if this is markup or the last element. + // + // This is because in Markup mode, we want to examine all nodes + // touching a replacement but in code we want to atomically replace. + if child_span.contains(self.replace_range.start) + && (mode == TokenMode::Markup + || self.replace_range.start != child_span.end + || self.replace_range.len() == 0 + || i == last) + { + start = Some((i, offset)); + break; + } + + offset += child.len(); + child_at_start = child.kind().is_at_start(child_at_start); + } + + let (start_idx, start_offset) = start.ok_or(())?; + + for (i, child) in (green.children_mut()[start_idx ..]).iter_mut().enumerate() { + let i = i + start_idx; + let child_span = + Span::new(self.replace_range.source, offset, offset + child.len()); + + // Similarly to above, the end of the edit must be in the node but + // if it is at the edge and we are in markup node, we also want its + // neighbor! + if child_span.contains(self.replace_range.end) + && (mode != TokenMode::Markup + || self.replace_range.end != child_span.end + || i == last) + { + loop_result = Some(( + start_idx .. i + 1, + Span::new( + self.replace_range.source, + start_offset, + offset + child.len(), + ), + i == last && outermost, + child.kind().clone(), + )); + break; + } else if mode != TokenMode::Markup || !child.kind().post().markup_safe() { + break; + } + + offset += child.len(); + } + + let (child_idx_range, child_span, child_outermost, child_kind) = + loop_result.ok_or(())?; + + if child_idx_range.len() == 1 { + let idx = child_idx_range.start; + let child = &mut green.children_mut()[idx]; + + let old_len = child.len(); + // First, we try if the child has another, more specific applicable child. + if !child_kind.post().unsafe_interior() { + if let Ok(range) = match child { + Green::Node(n) => self.reparse_step( + Rc::make_mut(n), + start_offset, + kind.mode().unwrap_or(TokenMode::Code), + child_outermost, + ), + Green::Token(_) => Err(()), + } { + let new_len = child.len(); + green.update_child_len(new_len, old_len); + return Ok(range); + } + } + } + + debug_assert_ne!(child_idx_range.len(), 0); + + if mode == TokenMode::Code && child_idx_range.len() > 1 { + return Err(()); + } + + // We now have a child that we can replace and a function to do so. + let (func, policy) = + child_kind.reparsing_function(kind.mode().unwrap_or(TokenMode::Code)); + let func = func?; + + let src_span = inserted_span(child_span, self.replace_range, self.replace_len); + let recompile_range = if policy == Postcondition::AtomicPrimary { + src_span.start .. self.src.len() + } else { + src_span.to_range() + }; + + let (mut new_children, unterminated) = + func(&self.src[recompile_range], child_at_start).ok_or(())?; + + // Do not accept unclosed nodes if the old node did not use to be at the + // right edge of the tree. + if !child_outermost && unterminated { + return Err(()); + } + + let insertion = match check_invariants( + &new_children, + green.children(), + child_idx_range.clone(), + child_at_start, + mode, + src_span, + policy, + ) { + InvariantResult::Ok => Ok(new_children), + InvariantResult::UseFirst => Ok(vec![std::mem::take(&mut new_children[0])]), + InvariantResult::Error => Err(()), + }?; + + green.replace_child_range(child_idx_range, insertion); + + Ok(src_span.to_range()) + } +} + +#[derive(Debug, Copy, Clone, PartialEq, Eq)] +enum InvariantResult { + Ok, + UseFirst, + Error, +} + +fn check_invariants( + use_children: &[Green], + old_children: &[Green], + child_idx_range: Range, + child_at_start: bool, + mode: TokenMode, + src_span: Span, + policy: Postcondition, +) -> InvariantResult { + let (new_children, ok) = if policy == Postcondition::AtomicPrimary { + if use_children.iter().map(Green::len).sum::() == src_span.len() { + (use_children, InvariantResult::Ok) + } else if use_children.len() == 1 && use_children[0].len() == src_span.len() { + (&use_children[0 .. 1], InvariantResult::UseFirst) + } else { + return InvariantResult::Error; + } + } else { + (use_children, InvariantResult::Ok) + }; + + let child_mode = old_children[child_idx_range.start] + .kind() + .mode() + .unwrap_or(TokenMode::Code); + + // Check if the children / child has the right type. + let same_kind = match policy { + Postcondition::SameKind(x) => x.map_or(true, |x| x == child_mode), + _ => false, + }; + + if same_kind || policy == Postcondition::AtomicPrimary { + if new_children.len() != 1 { + return InvariantResult::Error; + } + + if same_kind { + if old_children[child_idx_range.start].kind() != new_children[0].kind() { + return InvariantResult::Error; + } + } + } + + // Check if the neighbor invariants are still true. + if mode == TokenMode::Markup { + if child_idx_range.start > 0 { + if old_children[child_idx_range.start - 1].kind().pre() + == Precondition::RightWhitespace + && !new_children[0].kind().is_whitespace() + { + return InvariantResult::Error; + } + } + + if new_children.last().map(|x| x.kind().pre()) + == Some(Precondition::RightWhitespace) + && old_children.len() > child_idx_range.end + { + if !old_children[child_idx_range.end].kind().is_whitespace() { + return InvariantResult::Error; + } + } + + let mut new_at_start = child_at_start; + for child in new_children { + new_at_start = child.kind().is_at_start(new_at_start); + } + + for child in &old_children[child_idx_range.end ..] { + if child.kind().is_trivia() { + new_at_start = child.kind().is_at_start(new_at_start); + continue; + } + + match child.kind().pre() { + Precondition::AtStart if !new_at_start => { + return InvariantResult::Error; + } + Precondition::NotAtStart if new_at_start => { + return InvariantResult::Error; + } + _ => {} + } + break; + } + } + + ok +} + +/// Create a new span by specifying a span in which a modification happened +/// and how many characters are now in that span. +fn inserted_span(mut source: Span, other: Span, n: usize) -> Span { + if !source.surrounds(other) { + panic!(); + } + + let len_change = n as i64 - other.len() as i64; + source.end = (source.end as i64 + len_change) as usize; + source +} + +impl NodeKind { + /// Return the correct reparsing function given the postconditions for the + /// type. + fn reparsing_function( + &self, + parent_mode: TokenMode, + ) -> ( + Result Option<(Vec, bool)>, ()>, + Postcondition, + ) { + let policy = self.post(); + let mode = self.mode().unwrap_or(parent_mode); + + match policy { + Postcondition::Unsafe | Postcondition::UnsafeLayer => (Err(()), policy), + Postcondition::AtomicPrimary if mode == TokenMode::Code => { + (Ok(parse_atomic), policy) + } + Postcondition::AtomicPrimary => (Ok(parse_atomic_markup), policy), + Postcondition::SameKind(x) if x == None || x == Some(mode) => { + let parser: fn(&str, bool) -> _ = match self { + NodeKind::Template => parse_template, + NodeKind::Block => parse_block, + NodeKind::LineComment | NodeKind::BlockComment => parse_comment, + _ => return (Err(()), policy), + }; + + (Ok(parser), policy) + } + _ => { + let parser: fn(&str, bool) -> _ = match mode { + TokenMode::Markup if self == &Self::Markup => parse_markup, + TokenMode::Markup => parse_markup_elements, + _ => return (Err(()), policy), + }; + + (Ok(parser), policy) + } + } + } + + /// Whether it is safe to do incremental parsing on this node. Never allow + /// non-termination errors if this is not already the last leaf node. + pub fn post(&self) -> Postcondition { + match self { + // Replacing parenthesis changes if the expression is balanced and + // is therefore not safe. + Self::LeftBracket + | Self::RightBracket + | Self::LeftBrace + | Self::RightBrace + | Self::LeftParen + | Self::RightParen => Postcondition::Unsafe, + + // Replacing an operator can change whether the parent is an + // operation which makes it unsafe. The star can appear in markup. + Self::Star + | Self::Comma + | Self::Semicolon + | Self::Colon + | Self::Plus + | Self::Minus + | Self::Slash + | Self::Eq + | Self::EqEq + | Self::ExclEq + | Self::Lt + | Self::LtEq + | Self::Gt + | Self::GtEq + | Self::PlusEq + | Self::HyphEq + | Self::StarEq + | Self::SlashEq + | Self::Not + | Self::And + | Self::Or + | Self::With + | Self::Dots + | Self::Arrow => Postcondition::Unsafe, + + // These keywords are literals and can be safely be substituted with + // other expressions. + Self::None | Self::Auto => Postcondition::AtomicPrimary, + + // These keywords change what kind of expression the parent is and + // how far the expression would go. + Self::Let + | Self::Set + | Self::If + | Self::Else + | Self::For + | Self::In + | Self::While + | Self::Break + | Self::Continue + | Self::Return + | Self::Import + | Self::Include + | Self::From => Postcondition::Unsafe, + + Self::Markup => Postcondition::SameKind(None), + + Self::Space(_) => Postcondition::SameKind(Some(TokenMode::Code)), + + // These are all replaceable by other tokens. + Self::Parbreak + | Self::Linebreak + | Self::Text(_) + | Self::TextInLine(_) + | Self::NonBreakingSpace + | Self::EnDash + | Self::EmDash + | Self::Escape(_) + | Self::Strong + | Self::Emph + | Self::Heading + | Self::Enum + | Self::List + | Self::Raw(_) + | Self::Math(_) => Postcondition::Safe, + + // Changing the heading level, enum numbering, or list bullet + // changes the next layer. + Self::EnumNumbering(_) => Postcondition::Unsafe, + + // These are expressions that can be replaced by other expressions. + Self::Ident(_) + | Self::Bool(_) + | Self::Int(_) + | Self::Float(_) + | Self::Length(_, _) + | Self::Angle(_, _) + | Self::Percentage(_) + | Self::Str(_) + | Self::Fraction(_) + | Self::Array + | Self::Dict + | Self::Group => Postcondition::AtomicPrimary, + + Self::Call + | Self::Unary + | Self::Binary + | Self::CallArgs + | Self::Named + | Self::Spread => Postcondition::UnsafeLayer, + + // The closure is a bit magic with the let expression, and also it + // is not atomic. + Self::Closure | Self::ClosureParams => Postcondition::UnsafeLayer, + + // These can appear as bodies and would trigger an error if they + // became something else. + Self::Template => Postcondition::SameKind(None), + Self::Block => Postcondition::SameKind(Some(TokenMode::Code)), + + Self::ForExpr + | Self::WhileExpr + | Self::IfExpr + | Self::LetExpr + | Self::SetExpr + | Self::ImportExpr + | Self::IncludeExpr => Postcondition::AtomicPrimary, + + Self::WithExpr | Self::ForPattern | Self::ImportItems => { + Postcondition::UnsafeLayer + } + + // These can appear everywhere and must not change to other stuff + // because that could change the outer expression. + Self::LineComment | Self::BlockComment => Postcondition::SameKind(None), + + Self::Error(_, _) | Self::Unknown(_) => Postcondition::Unsafe, + } + } + + /// The appropriate precondition for the type. + pub fn pre(&self) -> Precondition { + match self { + Self::Heading | Self::Enum | Self::List => Precondition::AtStart, + Self::TextInLine(_) => Precondition::NotAtStart, + Self::Linebreak => Precondition::RightWhitespace, + _ => Precondition::None, + } + } +} + +/// The conditions that a node has to fulfill in order to be replaced. +/// +/// This can dictate if a node can be replaced at all and if yes, what can take +/// its place. +#[derive(Debug, Copy, Clone, Eq, PartialEq)] +pub enum Postcondition { + /// Changing this node can never have an influence on the other nodes. + Safe, + /// This node has to be replaced with a single token of the same kind. + SameKind(Option), + /// Changing this node into a single atomic expression is allowed if it + /// appears in code mode, otherwise it is safe. + AtomicPrimary, + /// Changing an unsafe layer node changes what the parents or the + /// surrounding nodes would be and is therefore disallowed. Change the + /// parents or children instead. If it appears in Markup, however, it is + /// safe to change. + UnsafeLayer, + /// Changing an unsafe node or any of its children will trigger undefined + /// behavior. Change the parents instead. + Unsafe, +} + +/// The conditions under which a node can be inserted or remain in a tree. +/// +/// These conditions all search the neighbors of the node and see if its +/// existence is plausible with them present. This can be used to encode some +/// context-free language components for incremental parsing. +#[derive(Debug, Copy, Clone, Eq, PartialEq)] +pub enum Precondition { + /// These nodes depend on being at the start of a line. Reparsing of safe + /// left neighbors has to check this invariant. Otherwise, this node is + /// safe. + AtStart, + /// These nodes depend on not being at the start of a line. Reparsing of + /// safe left neighbors has to check this invariant. Otherwise, this node is + /// safe. + NotAtStart, + /// These nodes must be followed by whitespace. + RightWhitespace, + /// No additional requirements. + None, +} + +impl Postcondition { + pub fn unsafe_interior(&self) -> bool { + match self { + Self::Unsafe => true, + _ => false, + } + } + + pub fn markup_safe(&self) -> bool { + match self { + Self::Safe | Self::UnsafeLayer => true, + Self::SameKind(tm) => tm.map_or(false, |tm| tm != TokenMode::Markup), + _ => false, + } + } +} + +#[cfg(test)] +mod tests { + use crate::parse::parse; + use crate::source::SourceFile; + + use super::*; + + #[test] + fn test_incremental_parse() { + #[track_caller] + fn test(prev: &str, range: Range, with: &str, incr: Range) { + let mut source = SourceFile::detached(prev); + let range = source.edit(range, with); + assert_eq!(range, incr); + + let incr_tree = source.root(); + assert_eq!(parse(source.src()), incr_tree); + } + + // Test simple replacements. + test("hello world", 6 .. 11, "wankers", 5 .. 13); + test("a d e", 1 .. 3, " b c d", 0 .. 8); + test("a #f() e", 1 .. 6, " b c d", 0 .. 8); + test("{(0, 1, 2)}", 5 .. 6, "11pt", 5 .. 9); + test("= A heading", 3 .. 3, "n evocative", 2 .. 15); + test("your thing", 5 .. 5, "a", 4 .. 11); + test("a your thing a", 6 .. 7, "a", 2 .. 12); + test("{call(); abc}", 7 .. 7, "[]", 0 .. 15); + test("#call() abc", 7 .. 7, "[]", 0 .. 13); + // test( + // "hi\n- item\n- item 2\n - item 3", + // 10 .. 10, + // " ", + // 9 .. 33, + // ); + test( + "#grid(columns: (auto, 1fr, 40%), [*plonk*], rect(width: 100%, height: 1pt, fill: conifer), [thing])", + 16 .. 20, + "none", + 16 .. 20, + ); + test( + "#grid(columns: (auto, 1fr, 40%), [*plonk*], rect(width: 100%, height: 1pt, fill: conifer), [thing])", + 33 .. 42, + "[_gronk_]", + 33 .. 42, + ); + test( + "#grid(columns: (auto, 1fr, 40%), [*plonk*], rect(width: 100%, height: 1pt, fill: conifer), [thing])", + 34 .. 41, + "_bar_", + 34 .. 39, + ); + test("{let i=1; for x in range(5) {i}}", 6 .. 6, " ", 1 .. 9); + test("{let i=1; for x in range(5) {i}}", 13 .. 14, " ", 13 .. 15); + test("hello {x}", 6 .. 9, "#f()", 5 .. 10); + test( + "this is -- in my opinion -- spectacular", + 8 .. 10, + "---", + 7 .. 12, + ); + test( + "understanding `code` is complicated", + 15 .. 15, + "C ", + 14 .. 22, + ); + test("{ let x = g() }", 10 .. 12, "f(54", 0 .. 17); + test( + "a #let rect with (fill: eastern)\nb", + 16 .. 31, + " (stroke: conifer", + 2 .. 34, + ); + + // Test the whitespace invariants. + test("hello \\ world", 7 .. 8, "a ", 6 .. 14); + test("hello \\ world", 7 .. 8, " a", 6 .. 14); + test("x = y", 1 .. 1, " + y", 0 .. 6); + test("x = y", 1 .. 1, " + y\n", 0 .. 10); + test("abc\n= a heading\njoke", 3 .. 4, "\nmore\n\n", 0 .. 21); + test("abc\n= a heading\njoke", 3 .. 4, "\nnot ", 0 .. 19); + test("hey #myfriend", 4 .. 4, "\\", 0 .. 14); + test("hey #myfriend", 4 .. 4, "\\", 3 .. 6); + + // Test type invariants. + test("a #for x in array {x}", 18 .. 21, "[#x]", 2 .. 22); + test("a #let x = 1 {5}", 3 .. 6, "if", 0 .. 15); + test("a {let x = 1 {5}} b", 3 .. 6, "if", 2 .. 16); + test("#let x = 1 {5}", 4 .. 4, " if", 0 .. 17); + test("{let x = 1 {5}}", 4 .. 4, " if", 0 .. 18); + test("a // b c #f()", 3 .. 4, "", 0 .. 12); + test("{\nf()\n//g(a)\n}", 6 .. 8, "", 0 .. 12); + test("a{\nf()\n//g(a)\n}b", 7 .. 9, "", 1 .. 13); + test("a #while x {\n g(x) \n} b", 11 .. 11, "//", 0 .. 26); + test("{(1, 2)}", 1 .. 1, "while ", 0 .. 14); + test("a b c", 1 .. 1, "{[}", 0 .. 5); + + // Test unclosed things. + test(r#"{"hi"}"#, 4 .. 5, "c", 0 .. 6); + test(r"this \u{abcd}", 8 .. 9, "", 5 .. 12); + test(r"this \u{abcd} that", 12 .. 13, "", 0 .. 17); + test(r"{{let x = z}; a = 1} b", 6 .. 6, "//", 0 .. 24); + test("a b c", 1 .. 1, " /* letters */", 0 .. 16); + test("a b c", 1 .. 1, " /* letters", 0 .. 16); + test( + "{if i==1 {a} else [b]; b()}", + 12 .. 12, + " /* letters */", + 1 .. 35, + ); + test( + "{if i==1 {a} else [b]; b()}", + 12 .. 12, + " /* letters", + 0 .. 38, + ); + + test(r#"a ```typst hello``` b"#, 16 .. 17, "", 0 .. 20); + test(r#"a ```typst hello```"#, 16 .. 17, "", 2 .. 18); + } +} -- cgit v1.2.3