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node_modules/micromark/dev/lib/create-tokenizer.js

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+/**
+ * @import {
+ *   Chunk,
+ *   Code,
+ *   ConstructRecord,
+ *   Construct,
+ *   Effects,
+ *   InitialConstruct,
+ *   ParseContext,
+ *   Point,
+ *   State,
+ *   TokenizeContext,
+ *   Token
+ * } from 'micromark-util-types'
+ */
+
+/**
+ * @callback Restore
+ *   Restore the state.
+ * @returns {undefined}
+ *   Nothing.
+ *
+ * @typedef Info
+ *   Info.
+ * @property {Restore} restore
+ *   Restore.
+ * @property {number} from
+ *   From.
+ *
+ * @callback ReturnHandle
+ *   Handle a successful run.
+ * @param {Construct} construct
+ *   Construct.
+ * @param {Info} info
+ *   Info.
+ * @returns {undefined}
+ *   Nothing.
+ */
+
+import createDebug from 'debug'
+import {ok as assert} from 'devlop'
+import {markdownLineEnding} from 'micromark-util-character'
+import {push, splice} from 'micromark-util-chunked'
+import {resolveAll} from 'micromark-util-resolve-all'
+import {codes, values} from 'micromark-util-symbol'
+
+const debug = createDebug('micromark')
+
+/**
+ * Create a tokenizer.
+ * Tokenizers deal with one type of data (e.g., containers, flow, text).
+ * The parser is the object dealing with it all.
+ * `initialize` works like other constructs, except that only its `tokenize`
+ * function is used, in which case it doesn’t receive an `ok` or `nok`.
+ * `from` can be given to set the point before the first character, although
+ * when further lines are indented, they must be set with `defineSkip`.
+ *
+ * @param {ParseContext} parser
+ *   Parser.
+ * @param {InitialConstruct} initialize
+ *   Construct.
+ * @param {Omit<Point, '_bufferIndex' | '_index'> | undefined} [from]
+ *   Point (optional).
+ * @returns {TokenizeContext}
+ *   Context.
+ */
+export function createTokenizer(parser, initialize, from) {
+  /** @type {Point} */
+  let point = {
+    _bufferIndex: -1,
+    _index: 0,
+    line: (from && from.line) || 1,
+    column: (from && from.column) || 1,
+    offset: (from && from.offset) || 0
+  }
+  /** @type {Record<string, number>} */
+  const columnStart = {}
+  /** @type {Array<Construct>} */
+  const resolveAllConstructs = []
+  /** @type {Array<Chunk>} */
+  let chunks = []
+  /** @type {Array<Token>} */
+  let stack = []
+  /** @type {boolean | undefined} */
+  let consumed = true
+
+  /**
+   * Tools used for tokenizing.
+   *
+   * @type {Effects}
+   */
+  const effects = {
+    attempt: constructFactory(onsuccessfulconstruct),
+    check: constructFactory(onsuccessfulcheck),
+    consume,
+    enter,
+    exit,
+    interrupt: constructFactory(onsuccessfulcheck, {interrupt: true})
+  }
+
+  /**
+   * State and tools for resolving and serializing.
+   *
+   * @type {TokenizeContext}
+   */
+  const context = {
+    code: codes.eof,
+    containerState: {},
+    defineSkip,
+    events: [],
+    now,
+    parser,
+    previous: codes.eof,
+    sliceSerialize,
+    sliceStream,
+    write
+  }
+
+  /**
+   * The state function.
+   *
+   * @type {State | undefined}
+   */
+  let state = initialize.tokenize.call(context, effects)
+
+  /**
+   * Track which character we expect to be consumed, to catch bugs.
+   *
+   * @type {Code}
+   */
+  let expectedCode
+
+  if (initialize.resolveAll) {
+    resolveAllConstructs.push(initialize)
+  }
+
+  return context
+
+  /** @type {TokenizeContext['write']} */
+  function write(slice) {
+    chunks = push(chunks, slice)
+
+    main()
+
+    // Exit if we’re not done, resolve might change stuff.
+    if (chunks[chunks.length - 1] !== codes.eof) {
+      return []
+    }
+
+    addResult(initialize, 0)
+
+    // Otherwise, resolve, and exit.
+    context.events = resolveAll(resolveAllConstructs, context.events, context)
+
+    return context.events
+  }
+
+  //
+  // Tools.
+  //
+
+  /** @type {TokenizeContext['sliceSerialize']} */
+  function sliceSerialize(token, expandTabs) {
+    return serializeChunks(sliceStream(token), expandTabs)
+  }
+
+  /** @type {TokenizeContext['sliceStream']} */
+  function sliceStream(token) {
+    return sliceChunks(chunks, token)
+  }
+
+  /** @type {TokenizeContext['now']} */
+  function now() {
+    // This is a hot path, so we clone manually instead of `Object.assign({}, point)`
+    const {_bufferIndex, _index, line, column, offset} = point
+    return {_bufferIndex, _index, line, column, offset}
+  }
+
+  /** @type {TokenizeContext['defineSkip']} */
+  function defineSkip(value) {
+    columnStart[value.line] = value.column
+    accountForPotentialSkip()
+    debug('position: define skip: `%j`', point)
+  }
+
+  //
+  // State management.
+  //
+
+  /**
+   * Main loop (note that `_index` and `_bufferIndex` in `point` are modified by
+   * `consume`).
+   * Here is where we walk through the chunks, which either include strings of
+   * several characters, or numerical character codes.
+   * The reason to do this in a loop instead of a call is so the stack can
+   * drain.
+   *
+   * @returns {undefined}
+   *   Nothing.
+   */
+  function main() {
+    /** @type {number} */
+    let chunkIndex
+
+    while (point._index < chunks.length) {
+      const chunk = chunks[point._index]
+
+      // If we’re in a buffer chunk, loop through it.
+      if (typeof chunk === 'string') {
+        chunkIndex = point._index
+
+        if (point._bufferIndex < 0) {
+          point._bufferIndex = 0
+        }
+
+        while (
+          point._index === chunkIndex &&
+          point._bufferIndex < chunk.length
+        ) {
+          go(chunk.charCodeAt(point._bufferIndex))
+        }
+      } else {
+        go(chunk)
+      }
+    }
+  }
+
+  /**
+   * Deal with one code.
+   *
+   * @param {Code} code
+   *   Code.
+   * @returns {undefined}
+   *   Nothing.
+   */
+  function go(code) {
+    assert(consumed === true, 'expected character to be consumed')
+    consumed = undefined
+    debug('main: passing `%s` to %s', code, state && state.name)
+    expectedCode = code
+    assert(typeof state === 'function', 'expected state')
+    state = state(code)
+  }
+
+  /** @type {Effects['consume']} */
+  function consume(code) {
+    assert(code === expectedCode, 'expected given code to equal expected code')
+
+    debug('consume: `%s`', code)
+
+    assert(
+      consumed === undefined,
+      'expected code to not have been consumed: this might be because `return x(code)` instead of `return x` was used'
+    )
+    assert(
+      code === null
+        ? context.events.length === 0 ||
+            context.events[context.events.length - 1][0] === 'exit'
+        : context.events[context.events.length - 1][0] === 'enter',
+      'expected last token to be open'
+    )
+
+    if (markdownLineEnding(code)) {
+      point.line++
+      point.column = 1
+      point.offset += code === codes.carriageReturnLineFeed ? 2 : 1
+      accountForPotentialSkip()
+      debug('position: after eol: `%j`', point)
+    } else if (code !== codes.virtualSpace) {
+      point.column++
+      point.offset++
+    }
+
+    // Not in a string chunk.
+    if (point._bufferIndex < 0) {
+      point._index++
+    } else {
+      point._bufferIndex++
+
+      // At end of string chunk.
+      if (
+        point._bufferIndex ===
+        // Points w/ non-negative `_bufferIndex` reference
+        // strings.
+        /** @type {string} */ (chunks[point._index]).length
+      ) {
+        point._bufferIndex = -1
+        point._index++
+      }
+    }
+
+    // Expose the previous character.
+    context.previous = code
+
+    // Mark as consumed.
+    consumed = true
+  }
+
+  /** @type {Effects['enter']} */
+  function enter(type, fields) {
+    /** @type {Token} */
+    // @ts-expect-error Patch instead of assign required fields to help GC.
+    const token = fields || {}
+    token.type = type
+    token.start = now()
+
+    assert(typeof type === 'string', 'expected string type')
+    assert(type.length > 0, 'expected non-empty string')
+    debug('enter: `%s`', type)
+
+    context.events.push(['enter', token, context])
+
+    stack.push(token)
+
+    return token
+  }
+
+  /** @type {Effects['exit']} */
+  function exit(type) {
+    assert(typeof type === 'string', 'expected string type')
+    assert(type.length > 0, 'expected non-empty string')
+
+    const token = stack.pop()
+    assert(token, 'cannot close w/o open tokens')
+    token.end = now()
+
+    assert(type === token.type, 'expected exit token to match current token')
+
+    assert(
+      !(
+        token.start._index === token.end._index &&
+        token.start._bufferIndex === token.end._bufferIndex
+      ),
+      'expected non-empty token (`' + type + '`)'
+    )
+
+    debug('exit: `%s`', token.type)
+    context.events.push(['exit', token, context])
+
+    return token
+  }
+
+  /**
+   * Use results.
+   *
+   * @type {ReturnHandle}
+   */
+  function onsuccessfulconstruct(construct, info) {
+    addResult(construct, info.from)
+  }
+
+  /**
+   * Discard results.
+   *
+   * @type {ReturnHandle}
+   */
+  function onsuccessfulcheck(_, info) {
+    info.restore()
+  }
+
+  /**
+   * Factory to attempt/check/interrupt.
+   *
+   * @param {ReturnHandle} onreturn
+   *   Callback.
+   * @param {{interrupt?: boolean | undefined} | undefined} [fields]
+   *   Fields.
+   */
+  function constructFactory(onreturn, fields) {
+    return hook
+
+    /**
+     * Handle either an object mapping codes to constructs, a list of
+     * constructs, or a single construct.
+     *
+     * @param {Array<Construct> | ConstructRecord | Construct} constructs
+     *   Constructs.
+     * @param {State} returnState
+     *   State.
+     * @param {State | undefined} [bogusState]
+     *   State.
+     * @returns {State}
+     *   State.
+     */
+    function hook(constructs, returnState, bogusState) {
+      /** @type {ReadonlyArray<Construct>} */
+      let listOfConstructs
+      /** @type {number} */
+      let constructIndex
+      /** @type {Construct} */
+      let currentConstruct
+      /** @type {Info} */
+      let info
+
+      return Array.isArray(constructs)
+        ? /* c8 ignore next 1 */
+          handleListOfConstructs(constructs)
+        : 'tokenize' in constructs
+          ? // Looks like a construct.
+            handleListOfConstructs([/** @type {Construct} */ (constructs)])
+          : handleMapOfConstructs(constructs)
+
+      /**
+       * Handle a list of construct.
+       *
+       * @param {ConstructRecord} map
+       *   Constructs.
+       * @returns {State}
+       *   State.
+       */
+      function handleMapOfConstructs(map) {
+        return start
+
+        /** @type {State} */
+        function start(code) {
+          const left = code !== null && map[code]
+          const all = code !== null && map.null
+          const list = [
+            // To do: add more extension tests.
+            /* c8 ignore next 2 */
+            ...(Array.isArray(left) ? left : left ? [left] : []),
+            ...(Array.isArray(all) ? all : all ? [all] : [])
+          ]
+
+          return handleListOfConstructs(list)(code)
+        }
+      }
+
+      /**
+       * Handle a list of construct.
+       *
+       * @param {ReadonlyArray<Construct>} list
+       *   Constructs.
+       * @returns {State}
+       *   State.
+       */
+      function handleListOfConstructs(list) {
+        listOfConstructs = list
+        constructIndex = 0
+
+        if (list.length === 0) {
+          assert(bogusState, 'expected `bogusState` to be given')
+          return bogusState
+        }
+
+        return handleConstruct(list[constructIndex])
+      }
+
+      /**
+       * Handle a single construct.
+       *
+       * @param {Construct} construct
+       *   Construct.
+       * @returns {State}
+       *   State.
+       */
+      function handleConstruct(construct) {
+        return start
+
+        /** @type {State} */
+        function start(code) {
+          // To do: not needed to store if there is no bogus state, probably?
+          // Currently doesn’t work because `inspect` in document does a check
+          // w/o a bogus, which doesn’t make sense. But it does seem to help perf
+          // by not storing.
+          info = store()
+          currentConstruct = construct
+
+          if (!construct.partial) {
+            context.currentConstruct = construct
+          }
+
+          // Always populated by defaults.
+          assert(
+            context.parser.constructs.disable.null,
+            'expected `disable.null` to be populated'
+          )
+
+          if (
+            construct.name &&
+            context.parser.constructs.disable.null.includes(construct.name)
+          ) {
+            return nok(code)
+          }
+
+          return construct.tokenize.call(
+            // If we do have fields, create an object w/ `context` as its
+            // prototype.
+            // This allows a “live binding”, which is needed for `interrupt`.
+            fields ? Object.assign(Object.create(context), fields) : context,
+            effects,
+            ok,
+            nok
+          )(code)
+        }
+      }
+
+      /** @type {State} */
+      function ok(code) {
+        assert(code === expectedCode, 'expected code')
+        consumed = true
+        onreturn(currentConstruct, info)
+        return returnState
+      }
+
+      /** @type {State} */
+      function nok(code) {
+        assert(code === expectedCode, 'expected code')
+        consumed = true
+        info.restore()
+
+        if (++constructIndex < listOfConstructs.length) {
+          return handleConstruct(listOfConstructs[constructIndex])
+        }
+
+        return bogusState
+      }
+    }
+  }
+
+  /**
+   * @param {Construct} construct
+   *   Construct.
+   * @param {number} from
+   *   From.
+   * @returns {undefined}
+   *   Nothing.
+   */
+  function addResult(construct, from) {
+    if (construct.resolveAll && !resolveAllConstructs.includes(construct)) {
+      resolveAllConstructs.push(construct)
+    }
+
+    if (construct.resolve) {
+      splice(
+        context.events,
+        from,
+        context.events.length - from,
+        construct.resolve(context.events.slice(from), context)
+      )
+    }
+
+    if (construct.resolveTo) {
+      context.events = construct.resolveTo(context.events, context)
+    }
+
+    assert(
+      construct.partial ||
+        context.events.length === 0 ||
+        context.events[context.events.length - 1][0] === 'exit',
+      'expected last token to end'
+    )
+  }
+
+  /**
+   * Store state.
+   *
+   * @returns {Info}
+   *   Info.
+   */
+  function store() {
+    const startPoint = now()
+    const startPrevious = context.previous
+    const startCurrentConstruct = context.currentConstruct
+    const startEventsIndex = context.events.length
+    const startStack = Array.from(stack)
+
+    return {from: startEventsIndex, restore}
+
+    /**
+     * Restore state.
+     *
+     * @returns {undefined}
+     *   Nothing.
+     */
+    function restore() {
+      point = startPoint
+      context.previous = startPrevious
+      context.currentConstruct = startCurrentConstruct
+      context.events.length = startEventsIndex
+      stack = startStack
+      accountForPotentialSkip()
+      debug('position: restore: `%j`', point)
+    }
+  }
+
+  /**
+   * Move the current point a bit forward in the line when it’s on a column
+   * skip.
+   *
+   * @returns {undefined}
+   *   Nothing.
+   */
+  function accountForPotentialSkip() {
+    if (point.line in columnStart && point.column < 2) {
+      point.column = columnStart[point.line]
+      point.offset += columnStart[point.line] - 1
+    }
+  }
+}
+
+/**
+ * Get the chunks from a slice of chunks in the range of a token.
+ *
+ * @param {ReadonlyArray<Chunk>} chunks
+ *   Chunks.
+ * @param {Pick<Token, 'end' | 'start'>} token
+ *   Token.
+ * @returns {Array<Chunk>}
+ *   Chunks.
+ */
+function sliceChunks(chunks, token) {
+  const startIndex = token.start._index
+  const startBufferIndex = token.start._bufferIndex
+  const endIndex = token.end._index
+  const endBufferIndex = token.end._bufferIndex
+  /** @type {Array<Chunk>} */
+  let view
+
+  if (startIndex === endIndex) {
+    assert(endBufferIndex > -1, 'expected non-negative end buffer index')
+    assert(startBufferIndex > -1, 'expected non-negative start buffer index')
+    // @ts-expect-error `_bufferIndex` is used on string chunks.
+    view = [chunks[startIndex].slice(startBufferIndex, endBufferIndex)]
+  } else {
+    view = chunks.slice(startIndex, endIndex)
+
+    if (startBufferIndex > -1) {
+      const head = view[0]
+      if (typeof head === 'string') {
+        view[0] = head.slice(startBufferIndex)
+        /* c8 ignore next 4 -- used to be used, no longer */
+      } else {
+        assert(startBufferIndex === 0, 'expected `startBufferIndex` to be `0`')
+        view.shift()
+      }
+    }
+
+    if (endBufferIndex > 0) {
+      // @ts-expect-error `_bufferIndex` is used on string chunks.
+      view.push(chunks[endIndex].slice(0, endBufferIndex))
+    }
+  }
+
+  return view
+}
+
+/**
+ * Get the string value of a slice of chunks.
+ *
+ * @param {ReadonlyArray<Chunk>} chunks
+ *   Chunks.
+ * @param {boolean | undefined} [expandTabs=false]
+ *   Whether to expand tabs (default: `false`).
+ * @returns {string}
+ *   Result.
+ */
+function serializeChunks(chunks, expandTabs) {
+  let index = -1
+  /** @type {Array<string>} */
+  const result = []
+  /** @type {boolean | undefined} */
+  let atTab
+
+  while (++index < chunks.length) {
+    const chunk = chunks[index]
+    /** @type {string} */
+    let value
+
+    if (typeof chunk === 'string') {
+      value = chunk
+    } else
+      switch (chunk) {
+        case codes.carriageReturn: {
+          value = values.cr
+
+          break
+        }
+
+        case codes.lineFeed: {
+          value = values.lf
+
+          break
+        }
+
+        case codes.carriageReturnLineFeed: {
+          value = values.cr + values.lf
+
+          break
+        }
+
+        case codes.horizontalTab: {
+          value = expandTabs ? values.space : values.ht
+
+          break
+        }
+
+        case codes.virtualSpace: {
+          if (!expandTabs && atTab) continue
+          value = values.space
+
+          break
+        }
+
+        default: {
+          assert(typeof chunk === 'number', 'expected number')
+          // Currently only replacement character.
+          value = String.fromCharCode(chunk)
+        }
+      }
+
+    atTab = chunk === codes.horizontalTab
+    result.push(value)
+  }
+
+  return result.join('')
+}