316 lines
16 KiB
TypeScript
316 lines
16 KiB
TypeScript
import type { AdfMark, AdfNode } from './adf-document.ts'
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import type { InlineDirective } from './inline-directives.ts'
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import { assembleInlineLine, type InlineEscaping, type InlineSegment, type LineContainer } from './markdown-escaping.ts'
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import { inlineDirective, markSpelling, spellInlineNodeAttributes, spellMarkAttributes } from './inline-directives.ts'
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import { largestNesting } from './nesting.ts'
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import { claimsLine, holdsControlCharacter, holdsEntityReference, holdsNullCharacter, isAutolink, isUnicodeWhitespace } from './commonmark-grammar.ts'
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import { carriedInline } from './opaque-carry.ts'
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import { failure, success, type ConvertErrorPath, type Result } from './result.ts'
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import { longestBacktickRun } from './backtick-runs.ts'
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import { serializeCanonicalJson } from './canonical-json.ts'
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import { spellAttributes, spellStringAttribute } from './directive-attributes.ts'
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type InlineContext = {
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atBlockEnd: boolean
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bracketed: boolean
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path: ConvertErrorPath
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spansLines: boolean
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}
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type InlineRun = { index: number; kind: 'marked'; mark: AdfMark; nodes: AdfNode[] } | { index: number; kind: 'plain'; node: AdfNode }
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export function emitInlineLine(nodes: readonly AdfNode[], container: LineContainer, path: ConvertErrorPath): Result<string> {
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const segments = lineSegments(nodes, container, path)
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if (!segments.ok) return segments
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return finishLine(segments.value, container, path)
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}
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export function tryPipeCell(nodes: readonly AdfNode[], path: ConvertErrorPath): string | undefined {
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const segments = lineSegments(nodes, 'table-cell', path)
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if (!segments.ok) return undefined
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if (segments.value.some((segment) => segment.escaping === 'none' && segment.text.includes('|'))) return undefined
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const line = finishLine(segments.value, 'table-cell', path)
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return line.ok ? line.value : undefined
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}
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export function tryImageLine(alt: string | undefined, href: string, path: ConvertErrorPath): string | undefined {
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if (alt !== undefined && (/^[ \t]|[ \t]$|[\n\r]/.test(alt) || holdsNullCharacter(alt))) return undefined
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const destination = spellDestination(href, path)
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if (!destination.ok) return undefined
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const description: InlineSegment[] = alt === undefined ? [] : [{ escaping: 'bracketed', text: alt }]
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const line = finishLine([syntax('`)], 'paragraph', path)
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return line.ok ? line.value : undefined
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}
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function lineSegments(nodes: readonly AdfNode[], container: LineContainer, path: ConvertErrorPath): Result<InlineSegment[]> {
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const segments = emitRun(nodes, 0, 0, { atBlockEnd: true, bracketed: false, path, spansLines: container === 'paragraph' })
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if (!segments.ok) return segments
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return success(carryStrippedWhitespace(segments.value))
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}
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function finishLine(segments: readonly InlineSegment[], container: LineContainer, path: ConvertErrorPath): Result<string> {
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const assembled = assembleInlineLine(segments, container)
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if (assembled.unspellableMark !== undefined) {
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return failure('unspellable-mark', `the ${assembled.unspellableMark} spelling cannot open or close where it sits`, path)
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}
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const line = assembled.line
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for (const [index, single] of line.split('\n').entries()) {
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if (/^[ \t\v\f]|[ \t\v\f]$/.test(single)) {
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return failure('unspellable-whitespace', 'a line begins or ends with whitespace CommonMark strips', path)
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}
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if (container === 'paragraph' && claimsLine(single, index === 0 ? 'first' : 'later')) {
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return failure('unspellable-line-start', `block parsing would claim the emitted line ${JSON.stringify(single)}`, path)
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}
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}
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return success(line)
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}
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// spec/flavour.md, Inline nodes.
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function carryStrippedWhitespace(segments: readonly InlineSegment[]): InlineSegment[] {
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const carried: InlineSegment[] = []
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for (const [index, segment] of segments.entries()) {
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const previous = segments[index - 1]
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const next = segments[index + 1]
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const leading = previous === undefined || previous.text.includes('\n')
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const trailing = next === undefined || next.text.includes('\n')
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carried.push(...carryEdges(segment, leading, trailing))
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}
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return carried
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}
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function carryEdges(segment: InlineSegment, leading: boolean, trailing: boolean): InlineSegment[] {
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if (segment.escaping !== 'backslash' && segment.escaping !== 'bracketed') return [segment]
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const head = leading ? (/^[ \t]+/.exec(segment.text)?.[0] ?? '') : ''
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const body = segment.text.slice(head.length)
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const tail = trailing ? (/[ \t]+$/.exec(body)?.[0] ?? '') : ''
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const middle = body.slice(0, body.length - tail.length)
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const edges: InlineSegment[] = []
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if (head !== '') edges.push(carriedText(head))
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if (middle !== '') edges.push({ escaping: segment.escaping, text: middle })
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if (tail !== '') edges.push(carriedText(tail))
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return edges
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}
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function carriedText(text: string): InlineSegment {
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return syntax(spellLeafDirective('text', spellAttributes([['text', spellStringAttribute(text)]])))
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}
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function spellLeafDirective(name: string, attributes: string): string {
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return `:${name}${attributes === '' ? '{}' : attributes}`
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}
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function syntax(text: string): InlineSegment {
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return { escaping: 'none', text }
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}
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function refuseContentAndText(node: AdfNode, path: ConvertErrorPath): Result<null> {
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if ((node.content ?? []).length > 0 || node.text !== undefined) {
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return failure('unsupported-node-shape', `a ${node.type} node holds neither content nor text`, path)
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}
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return success(null)
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}
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function emitRun(nodes: readonly AdfNode[], depth: number, firstIndex: number, context: InlineContext): Result<InlineSegment[]> {
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if (depth > largestNesting) {
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return failure('unsupported-node-shape', `the marks nest deeper than the ${largestNesting} levels the emitter carries`, context.path)
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}
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const runs = inlineRuns(nodes, depth, firstIndex)
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const segments: InlineSegment[] = []
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for (const [offset, run] of runs.entries()) {
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const runContext = { ...context, atBlockEnd: context.atBlockEnd && offset === runs.length - 1 }
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const emitted = run.kind === 'plain' ? emitLeaf(run.node, runContext, run.index) : emitMarkedRun(run.nodes, run.mark, depth, run.index, runContext)
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if (!emitted.ok) return emitted
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segments.push(...emitted.value)
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}
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return success(segments)
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}
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function inlineRuns(nodes: readonly AdfNode[], depth: number, firstIndex: number): InlineRun[] {
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const runs: InlineRun[] = []
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for (const [offset, node] of nodes.entries()) {
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const index = firstIndex + offset
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// spec/flavour.md, Marks.
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const mark = carries(node) ? undefined : (node.marks ?? [])[depth]
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if (mark === undefined) {
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runs.push({ index, kind: 'plain', node })
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continue
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}
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const previous = runs[runs.length - 1]
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if (previous?.kind === 'marked' && sameMark(previous.mark, mark)) previous.nodes.push(node)
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else runs.push({ index, kind: 'marked', mark, nodes: [node] })
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}
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return runs
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}
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function nodePath(context: InlineContext, index: number): ConvertErrorPath {
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return [...context.path, 'content', index]
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}
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function carries(node: AdfNode): boolean {
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return node.type !== 'hardBreak' && node.type !== 'text' && inlineDirective(node.type) === undefined
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}
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function emitLeaf(node: AdfNode, context: InlineContext, index: number): Result<InlineSegment[]> {
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const path = nodePath(context, index)
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if (carries(node)) {
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const carried = carriedInline(node, path)
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if (!carried.ok) return carried
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return success([syntax(carried.value)])
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}
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const types = (node.marks ?? []).map((mark) => mark.type)
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if (new Set(types).size !== types.length) return failure('unsupported-node-shape', `a ${node.type} node carries one mark type twice`, path)
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const directive = inlineDirective(node.type)
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if (directive !== undefined) return emitInlineDirective(node, directive, path)
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if (node.type === 'hardBreak') return emitHardBreak(node, context, path)
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return emitText(node, context, path)
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}
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function emitHardBreak(node: AdfNode, context: InlineContext, path: ConvertErrorPath): Result<InlineSegment[]> {
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const unspelled = Object.keys(node.attrs ?? {})[0]
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if (unspelled !== undefined) return failure('unspelled-node-attribute', `the hardBreak attribute ${unspelled} has no canonical markdown spelling`, path)
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const empty = refuseContentAndText(node, path)
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if (!empty.ok) return empty
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if (context.spansLines && !context.atBlockEnd) return success([syntax('\\\n')])
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return success([syntax(spellLeafDirective('hardBreak', ''))])
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}
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function emitInlineDirective(node: AdfNode, directive: InlineDirective, path: ConvertErrorPath): Result<InlineSegment[]> {
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const empty = refuseContentAndText(node, path)
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if (!empty.ok) return empty
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const attributes = spellInlineNodeAttributes(node, directive, path)
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if (!attributes.ok) return attributes
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const slot = directive.slot === undefined ? undefined : node.attrs?.[directive.slot]
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if (slot === undefined) return success([syntax(spellLeafDirective(node.type, attributes.value))])
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if (typeof slot !== 'string') return failure('unsupported-node-shape', `the ${node.type} attribute ${directive.slot} holds no string`, path)
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if (/[\n\r]/.test(slot)) return failure('unspellable-whitespace', `a ${node.type} content slot holds a newline no inline directive spans`, path)
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if (holdsNullCharacter(slot)) return failure('unspellable-character', `a ${node.type} content slot holds a null character CommonMark replaces`, path)
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const content: InlineSegment[] = slot === '' ? [] : [{ escaping: 'bracketed', text: slot }]
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return success([syntax(`:${node.type}[`), ...content, syntax(`]${attributes.value}`)])
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}
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function emitText(node: AdfNode, context: InlineContext, path: ConvertErrorPath): Result<InlineSegment[]> {
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const unspelled = Object.keys(node.attrs ?? {})[0]
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if (unspelled !== undefined) return failure('unspelled-node-attribute', `the text attribute ${unspelled} has no canonical markdown spelling`, path)
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if (typeof node.text !== 'string' || node.text === '') return failure('unsupported-node-shape', 'a text node holds text', path)
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if ((node.content ?? []).length > 0) return failure('unsupported-node-shape', 'a text node holds no content', path)
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if (/\r/.test(node.text)) return failure('unspellable-whitespace', 'a text node holds a carriage return CommonMark rewrites', path)
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if (holdsNullCharacter(node.text)) return failure('unspellable-character', 'a text node holds a null character CommonMark replaces', path)
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const escaping: InlineEscaping = context.bracketed ? 'bracketed' : 'backslash'
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const parts = node.text.split(/(\n+)/).filter((part) => part !== '')
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return success(parts.map((part) => (part.startsWith('\n') ? carriedText(part) : { escaping, text: part })))
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}
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function emitMarkedRun(nodes: readonly AdfNode[], mark: AdfMark, depth: number, index: number, context: InlineContext): Result<InlineSegment[]> {
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const path = nodePath(context, index)
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const spelling = markSpelling(mark.type)
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if (spelling === undefined) return failure('unspellable-mark', `no markdown spelling holds the ${mark.type} mark`, path)
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const attributes = spellMarkAttributes(mark, spelling.attributes, path)
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if (!attributes.ok) return attributes
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if (spelling.kind === 'code') return emitCodeSpan(nodes, depth, path)
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if (spelling.kind === 'emphasis') return emitEmphasis(nodes, mark, spelling.spelling, depth, index, context, path)
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if (spelling.kind === 'link') return emitLink(nodes, mark, depth, index, context, path)
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const inner = emitRun(nodes, depth + 1, index, { ...context, bracketed: true, spansLines: false })
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if (!inner.ok) return inner
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return success([syntax(`:${mark.type}[`), ...inner.value, syntax(`]${attributes.value}`)])
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}
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function emitEmphasis(
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nodes: readonly AdfNode[],
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mark: AdfMark,
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spelling: string,
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depth: number,
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index: number,
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context: InlineContext,
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path: ConvertErrorPath,
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): Result<InlineSegment[]> {
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const inner = emitRun(nodes, depth + 1, index, context)
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if (!inner.ok) return inner
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const carried = carryStrippedWhitespace(inner.value)
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const text = carried.map((segment) => segment.text).join('')
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if (holdsEdgeWhitespace(text)) return failure('unspellable-whitespace', `the ${mark.type} spelling cannot open or close beside whitespace`, path)
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return success([
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{ emphasis: 'open', escaping: 'none', mark: mark.type, text: spelling },
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...carried,
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{ emphasis: 'close', escaping: 'none', mark: mark.type, text: spelling },
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])
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}
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function emitCodeSpan(nodes: readonly AdfNode[], depth: number, path: ConvertErrorPath): Result<InlineSegment[]> {
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let text = ''
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for (const node of nodes) {
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if (node.type !== 'text' || typeof node.text !== 'string' || node.text === '') return failure('unspellable-mark', 'a code span holds text nodes only', path)
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if ((node.marks ?? []).length !== depth + 1) return failure('unspellable-mark', 'a code span cannot sit inside the marks it carries', path)
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text += node.text
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}
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if (/[\n\r]/.test(text)) return failure('unspellable-mark', 'a code span holds no newline', path)
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if (holdsNullCharacter(text)) return failure('unspellable-character', 'a code span holds a null character CommonMark replaces', path)
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const fence = '`'.repeat(longestBacktickRun(text) + 1)
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const padded = needsPadding(text) ? ` ${text} ` : text
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return success([syntax(`${fence}${padded}${fence}`)])
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}
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function holdsEdgeWhitespace(text: string): boolean {
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return isUnicodeWhitespace(text.charAt(0)) || isUnicodeWhitespace(text.charAt(text.length - 1))
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}
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function needsPadding(text: string): boolean {
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if (text.startsWith('`') || text.endsWith('`')) return true
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return text.startsWith(' ') && text.endsWith(' ') && /[^ ]/.test(text)
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}
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function emitLink(nodes: readonly AdfNode[], mark: AdfMark, depth: number, index: number, context: InlineContext, path: ConvertErrorPath): Result<InlineSegment[]> {
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const href = mark.attrs?.['href']
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const title = mark.attrs?.['title']
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if (typeof href !== 'string') return failure('unsupported-node-shape', 'a link mark carries no href', path)
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const node = nodes[0]
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const bare = nodes.length === 1 && node !== undefined && node.type === 'text' && node.text === href && (node.marks ?? []).length === depth + 1
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if (bare && title === undefined && isAutolink(href) && !holdsEntityReference(href)) return success([syntax(`<${href}>`)])
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const destination = spellDestination(href, path)
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if (!destination.ok) return destination
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const spelledTitle = typeof title === 'string' ? spellTitle(title, path) : success('')
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if (!spelledTitle.ok) return spelledTitle
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const inner = emitRun(nodes, depth + 1, index, { ...context, bracketed: true })
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if (!inner.ok) return inner
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return success([syntax('['), ...inner.value, syntax(`](${destination.value}${spelledTitle.value})`)])
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}
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function spellDestination(href: string, path: ConvertErrorPath): Result<string> {
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if (holdsControlCharacter(href)) return failure('unspellable-link-destination', 'a link destination holds a control character', path)
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if (href.includes('\\')) return failure('unspellable-link-destination', 'no canonical escape spells a backslash in a link destination', path)
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if (holdsEntityReference(href)) {
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return failure('unspellable-link-destination', 'a link destination shaped like an entity reference decodes on the way back', path)
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}
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if (href.includes(' ')) {
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if (/[<>]/.test(href)) {
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return failure('unspellable-link-destination', 'no canonical escape spells an angle bracket beside a space in a link destination', path)
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}
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return success(`<${href}>`)
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}
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if (href.startsWith('<')) return failure('unspellable-link-destination', 'a bare link destination cannot begin with an angle bracket', path)
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if (!balanced(href)) return failure('unspellable-link-destination', 'no canonical escape spells an unbalanced parenthesis in a link destination', path)
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return success(href)
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}
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function spellTitle(title: string, path: ConvertErrorPath): Result<string> {
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if (/["\n\r\\]/.test(title)) {
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return failure('unspellable-link-title', 'no canonical escape spells a quote, backslash or newline in a link title', path)
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}
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if (holdsEntityReference(title)) return failure('unspellable-link-title', 'a link title shaped like an entity reference decodes on the way back', path)
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return success(` "${title}"`)
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}
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function balanced(href: string): boolean {
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let depth = 0
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for (const character of href) {
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if (character === '(') depth += 1
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if (character === ')') depth -= 1
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if (depth < 0) return false
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}
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return depth === 0
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}
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function sameMark(candidate: AdfMark, mark: AdfMark): boolean {
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if (candidate.type !== mark.type) return false
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return serializeCanonicalJson(candidate.attrs ?? {}, 'compact') === serializeCanonicalJson(mark.attrs ?? {}, 'compact')
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}
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