Restructure and streamline token expansion The purpose of this commit is to streamline the token expansion code, by removing aspects of the code that are no longer relevant, removing pointless duplication, and eliminating the need to pass the same arguments to `expand_syntax`. The first big-picture change in this commit is that instead of a handful of `expand_` functions, which take a TokensIterator and ExpandContext, a smaller number of methods on the `TokensIterator` do the same job. The second big-picture change in this commit is fully eliminating the coloring traits, making coloring a responsibility of the base expansion implementations. This also means that the coloring tracer is merged into the expansion tracer, so you can follow a single expansion and see how the expansion process produced colored tokens. One side effect of this change is that the expander itself is marginally more error-correcting. The error correction works by switching from structured expansion to `BackoffColoringMode` when an unexpected token is found, which guarantees that all spans of the source are colored, but may not be the most optimal error recovery strategy. That said, because `BackoffColoringMode` only extends as far as a closing delimiter (`)`, `]`, `}`) or pipe (`|`), it does result in fairly granular correction strategy. The current code still produces an `Err` (plus a complete list of colored shapes) from the parsing process if any errors are encountered, but this could easily be addressed now that the underlying expansion is error-correcting. This commit also colors any spans that are syntax errors in red, and causes the parser to include some additional information about what tokens were expected at any given point where an error was encountered, so that completions and hinting could be more robust in the future. Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com> Co-authored-by: Andrés N. Robalino <andres@androbtech.com>
160 lines
4.4 KiB
Rust
160 lines
4.4 KiB
Rust
use crate::hir::Expression;
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use crate::{
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hir,
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hir::syntax_shape::{
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ExpandSyntax, ExpressionContinuationShape, MemberShape, PathTailShape, PathTailSyntax,
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VariablePathShape,
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},
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hir::tokens_iterator::TokensIterator,
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};
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use hir::SpannedExpression;
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use nu_errors::ParseError;
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use nu_source::Span;
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#[derive(Debug, Copy, Clone)]
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pub struct CoerceBlockShape;
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impl ExpandSyntax for CoerceBlockShape {
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type Output = Result<SpannedExpression, ParseError>;
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fn name(&self) -> &'static str {
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"any block"
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}
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fn expand<'a, 'b>(
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&self,
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token_nodes: &mut TokensIterator<'_>,
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) -> Result<SpannedExpression, ParseError> {
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// is it just a block?
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token_nodes
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.expand_syntax(BlockShape)
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.or_else(|_| token_nodes.expand_syntax(ShorthandBlockShape))
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}
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}
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#[derive(Debug, Copy, Clone)]
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pub struct BlockShape;
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impl ExpandSyntax for BlockShape {
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type Output = Result<SpannedExpression, ParseError>;
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fn name(&self) -> &'static str {
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"block"
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}
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fn expand<'a, 'b>(
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&self,
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token_nodes: &'b mut TokensIterator<'a>,
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) -> Result<SpannedExpression, ParseError> {
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let exprs = token_nodes.block()?;
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Ok(hir::Expression::Block(exprs.item).into_expr(exprs.span))
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}
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}
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#[derive(Debug, Copy, Clone)]
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pub struct ShorthandBlockShape;
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impl ExpandSyntax for ShorthandBlockShape {
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type Output = Result<SpannedExpression, ParseError>;
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fn name(&self) -> &'static str {
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"shorthand block"
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}
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fn expand<'a, 'b>(
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&self,
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token_nodes: &'b mut TokensIterator<'a>,
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) -> Result<SpannedExpression, ParseError> {
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let mut current = token_nodes.expand_syntax(ShorthandPath)?;
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loop {
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match token_nodes.expand_syntax(ExpressionContinuationShape) {
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Result::Err(_) => break,
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Result::Ok(continuation) => current = continuation.append_to(current),
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}
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}
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let span = current.span;
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let block = hir::Expression::Block(vec![current]).into_expr(span);
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Ok(block)
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}
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}
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/// A shorthand for `$it.foo."bar"`, used inside of a shorthand block
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#[derive(Debug, Copy, Clone)]
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pub struct ShorthandPath;
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impl ExpandSyntax for ShorthandPath {
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type Output = Result<SpannedExpression, ParseError>;
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fn name(&self) -> &'static str {
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"shorthand path"
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}
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fn expand<'a, 'b>(
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&self,
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token_nodes: &'b mut TokensIterator<'a>,
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) -> Result<SpannedExpression, ParseError> {
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// if it's a variable path, that's the head part
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let path = token_nodes.expand_syntax(VariablePathShape);
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if let Ok(path) = path {
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return Ok(path);
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}
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// Synthesize the head of the shorthand path (`<member>` -> `$it.<member>`)
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let mut head = token_nodes.expand_syntax(ShorthandHeadShape)?;
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// Now that we've synthesized the head, of the path, proceed to expand the tail of the path
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// like any other path.
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let tail = token_nodes.expand_syntax(PathTailShape);
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match tail {
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Err(_) => Ok(head),
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Ok(PathTailSyntax { tail, span }) => {
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let span = head.span.until(span);
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// For each member that `PathTailShape` expanded, join it onto the existing expression
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// to form a new path
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for member in tail {
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head = Expression::dot_member(head, member).into_expr(span);
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}
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Ok(head)
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}
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}
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}
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}
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/// A shorthand for `$it.foo."bar"`, used inside of a shorthand block
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#[derive(Debug, Copy, Clone)]
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pub struct ShorthandHeadShape;
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impl ExpandSyntax for ShorthandHeadShape {
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type Output = Result<SpannedExpression, ParseError>;
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fn name(&self) -> &'static str {
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"shorthand head"
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}
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fn expand<'a, 'b>(
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&self,
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token_nodes: &'b mut TokensIterator<'a>,
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) -> Result<SpannedExpression, ParseError> {
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let head = token_nodes.expand_syntax(MemberShape)?;
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let head = head.to_path_member(&token_nodes.source());
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// Synthesize an `$it` expression
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let it = synthetic_it();
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let span = head.span;
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Ok(Expression::path(it, vec![head]).into_expr(span))
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}
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}
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fn synthetic_it() -> hir::SpannedExpression {
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Expression::it_variable(Span::unknown()).into_expr(Span::unknown())
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}
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