2020-10-14 12:23:59 -05:00
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//! Syntax highlighting for macro_rules!.
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use syntax::{SyntaxElement, SyntaxKind, SyntaxToken, TextRange, T};
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2021-01-09 05:44:01 -06:00
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use crate::{HighlightedRange, HlTag};
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2020-10-14 12:23:59 -05:00
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2020-10-14 15:21:58 -05:00
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#[derive(Default)]
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2020-10-14 12:23:59 -05:00
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pub(super) struct MacroRulesHighlighter {
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state: Option<MacroMatcherParseState>,
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}
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impl MacroRulesHighlighter {
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pub(super) fn init(&mut self) {
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2020-10-14 15:21:58 -05:00
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self.state = Some(MacroMatcherParseState::default());
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2020-10-14 12:23:59 -05:00
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}
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pub(super) fn advance(&mut self, token: &SyntaxToken) {
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if let Some(state) = self.state.as_mut() {
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update_macro_rules_state(state, token);
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}
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}
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pub(super) fn highlight(&self, element: SyntaxElement) -> Option<HighlightedRange> {
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if let Some(state) = self.state.as_ref() {
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if matches!(state.rule_state, RuleState::Matcher | RuleState::Expander) {
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if let Some(range) = is_metavariable(element) {
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return Some(HighlightedRange {
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range,
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2021-01-09 05:44:01 -06:00
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highlight: HlTag::UnresolvedReference.into(),
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2020-10-14 12:23:59 -05:00
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binding_hash: None,
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});
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}
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}
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}
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None
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}
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}
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struct MacroMatcherParseState {
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/// Opening and corresponding closing bracket of the matcher or expander of the current rule
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paren_ty: Option<(SyntaxKind, SyntaxKind)>,
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paren_level: usize,
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rule_state: RuleState,
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/// Whether we are inside the outer `{` `}` macro block that holds the rules
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in_invoc_body: bool,
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}
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2020-10-14 15:21:58 -05:00
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impl Default for MacroMatcherParseState {
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fn default() -> Self {
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2020-10-14 12:23:59 -05:00
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MacroMatcherParseState {
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paren_ty: None,
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paren_level: 0,
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in_invoc_body: false,
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rule_state: RuleState::None,
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}
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}
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}
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#[derive(Copy, Clone, Debug, PartialEq)]
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enum RuleState {
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Matcher,
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Expander,
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Between,
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None,
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}
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impl RuleState {
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fn transition(&mut self) {
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*self = match self {
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RuleState::Matcher => RuleState::Between,
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RuleState::Expander => RuleState::None,
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RuleState::Between => RuleState::Expander,
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RuleState::None => RuleState::Matcher,
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};
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}
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}
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fn update_macro_rules_state(state: &mut MacroMatcherParseState, tok: &SyntaxToken) {
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if !state.in_invoc_body {
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if tok.kind() == T!['{'] {
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state.in_invoc_body = true;
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}
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return;
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}
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match state.paren_ty {
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Some((open, close)) => {
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if tok.kind() == open {
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state.paren_level += 1;
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} else if tok.kind() == close {
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state.paren_level -= 1;
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if state.paren_level == 0 {
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state.rule_state.transition();
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state.paren_ty = None;
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}
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}
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}
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None => {
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match tok.kind() {
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T!['('] => {
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state.paren_ty = Some((T!['('], T![')']));
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}
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T!['{'] => {
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state.paren_ty = Some((T!['{'], T!['}']));
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}
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T!['['] => {
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state.paren_ty = Some((T!['['], T![']']));
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}
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_ => (),
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}
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if state.paren_ty.is_some() {
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state.paren_level = 1;
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state.rule_state.transition();
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}
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}
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}
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}
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fn is_metavariable(element: SyntaxElement) -> Option<TextRange> {
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let tok = element.as_token()?;
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match tok.kind() {
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kind if kind == SyntaxKind::IDENT || kind.is_keyword() => {
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if let Some(_dollar) = tok.prev_token().filter(|t| t.kind() == SyntaxKind::DOLLAR) {
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return Some(tok.text_range());
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}
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}
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_ => (),
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};
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None
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}
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