import { bracketMatching as bracketMatchingExtension, matchBrackets, type MatchResult, } from '@codemirror/language' import { Decoration, EditorView } from '@codemirror/view' import { EditorSelection, Extension, SelectionRange, type Range, } from '@codemirror/state' const matchingMark = Decoration.mark({ class: 'cm-matchingBracket' }) const nonmatchingMark = Decoration.mark({ class: 'cm-nonmatchingBracket' }) const FORWARDS = 1 const BACKWARDS = -1 type Direction = 1 | -1 /** * A built-in extension which decorates matching pairs of brackets when focused, * configured with a custom render function that combines adjacent pairs of matching markers * into a single decoration so there’s no border between them. */ export const bracketMatching = () => { return bracketMatchingExtension({ renderMatch: match => { const decorations: Range[] = [] if (matchedAdjacent(match)) { // combine an adjacent pair of matching markers into a single decoration decorations.push( matchingMark.range( Math.min(match.start.from, match.end.from), Math.max(match.start.to, match.end.to) ) ) } else { // default match rendering (defaultRenderMatch in @codemirror/matchbrackets) const mark = match.matched ? matchingMark : nonmatchingMark decorations.push(mark.range(match.start.from, match.start.to)) if (match.end) { decorations.push(mark.range(match.end.from, match.end.to)) } } return decorations }, }) } interface AdjacentMatchResult extends MatchResult { end: { from: number to: number } } const matchedAdjacent = (match: MatchResult): match is AdjacentMatchResult => Boolean( match.matched && match.end && (match.start.to === match.end.from || match.end.to === match.start.from) ) /** * A custom extension which handles double-click events on a matched bracket * and extends the selection to cover the contents of the bracket pair. */ export const bracketSelection = (): Extension[] => [ EditorView.domEventHandlers({ dblclick: (evt, view) => { const pos = view.posAtCoords({ x: evt.pageX, y: evt.pageY, }) if (!pos) return false const search = (direction: Direction, position: number) => { const match = matchBrackets(view.state, position, direction, { // Only look at data in the syntax tree, don't scan the text maxScanDistance: 0, }) if (match?.matched && match.end) { return EditorSelection.range( Math.min(match.start.from, match.end.from), Math.max(match.end.to, match.start.to) ) } return false } const dispatchSelection = (range: SelectionRange) => { view.dispatch({ selection: range, }) return true } // 1. Look forwards, from the character *behind* the cursor const forwardsExcludingBrackets = search(FORWARDS, pos - 1) if (forwardsExcludingBrackets) { return dispatchSelection( EditorSelection.range( forwardsExcludingBrackets.from + 1, forwardsExcludingBrackets.to - 1 ) ) } // 2. Look forwards, from the character *in front of* the cursor const forwardsIncludingBrackets = search(FORWARDS, pos) if (forwardsIncludingBrackets) { return dispatchSelection(forwardsIncludingBrackets) } // 3. Look backwards, from the character *behind* the cursor const backwardsIncludingBrackets = search(BACKWARDS, pos) if (backwardsIncludingBrackets) { return dispatchSelection(backwardsIncludingBrackets) } // 4. Look backwards, from the character *in front of* the cursor const backwardsExcludingBrackets = search(BACKWARDS, pos + 1) if (backwardsExcludingBrackets) { return dispatchSelection( EditorSelection.range( backwardsExcludingBrackets.from + 1, backwardsExcludingBrackets.to - 1 ) ) } return false }, }), EditorView.baseTheme({ '.cm-matchingBracket': { pointerEvents: 'none', }, }), ]