planning

node_modules/micromark/lib/tokenize/attention.js

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+'use strict'
+
+var assert = require('assert')
+var codes = require('../character/codes.js')
+var constants = require('../constant/constants.js')
+var types = require('../constant/types.js')
+var chunkedPush = require('../util/chunked-push.js')
+var chunkedSplice = require('../util/chunked-splice.js')
+var classifyCharacter = require('../util/classify-character.js')
+var movePoint = require('../util/move-point.js')
+var resolveAll = require('../util/resolve-all.js')
+var shallow = require('../util/shallow.js')
+
+function _interopDefaultLegacy(e) {
+  return e && typeof e === 'object' && 'default' in e ? e : {default: e}
+}
+
+var assert__default = /*#__PURE__*/ _interopDefaultLegacy(assert)
+
+var attention = {
+  name: 'attention',
+  tokenize: tokenizeAttention,
+  resolveAll: resolveAllAttention
+}
+
+// Take all events and resolve attention to emphasis or strong.
+function resolveAllAttention(events, context) {
+  var index = -1
+  var open
+  var group
+  var text
+  var openingSequence
+  var closingSequence
+  var use
+  var nextEvents
+  var offset
+
+  // Walk through all events.
+  //
+  // Note: performance of this is fine on an mb of normal markdown, but it’s
+  // a bottleneck for malicious stuff.
+  while (++index < events.length) {
+    // Find a token that can close.
+    if (
+      events[index][0] === 'enter' &&
+      events[index][1].type === 'attentionSequence' &&
+      events[index][1]._close
+    ) {
+      open = index
+
+      // Now walk back to find an opener.
+      while (open--) {
+        // Find a token that can open the closer.
+        if (
+          events[open][0] === 'exit' &&
+          events[open][1].type === 'attentionSequence' &&
+          events[open][1]._open &&
+          // If the markers are the same:
+          context.sliceSerialize(events[open][1]).charCodeAt(0) ===
+            context.sliceSerialize(events[index][1]).charCodeAt(0)
+        ) {
+          // If the opening can close or the closing can open,
+          // and the close size *is not* a multiple of three,
+          // but the sum of the opening and closing size *is* multiple of three,
+          // then don’t match.
+          if (
+            (events[open][1]._close || events[index][1]._open) &&
+            (events[index][1].end.offset - events[index][1].start.offset) % 3 &&
+            !(
+              (events[open][1].end.offset -
+                events[open][1].start.offset +
+                events[index][1].end.offset -
+                events[index][1].start.offset) %
+              3
+            )
+          ) {
+            continue
+          }
+
+          // Number of markers to use from the sequence.
+          use =
+            events[open][1].end.offset - events[open][1].start.offset > 1 &&
+            events[index][1].end.offset - events[index][1].start.offset > 1
+              ? 2
+              : 1
+
+          openingSequence = {
+            type: use > 1 ? types.strongSequence : types.emphasisSequence,
+            start: movePoint(shallow(events[open][1].end), -use),
+            end: shallow(events[open][1].end)
+          }
+          closingSequence = {
+            type: use > 1 ? types.strongSequence : types.emphasisSequence,
+            start: shallow(events[index][1].start),
+            end: movePoint(shallow(events[index][1].start), use)
+          }
+          text = {
+            type: use > 1 ? types.strongText : types.emphasisText,
+            start: shallow(events[open][1].end),
+            end: shallow(events[index][1].start)
+          }
+          group = {
+            type: use > 1 ? types.strong : types.emphasis,
+            start: shallow(openingSequence.start),
+            end: shallow(closingSequence.end)
+          }
+
+          events[open][1].end = shallow(openingSequence.start)
+          events[index][1].start = shallow(closingSequence.end)
+
+          nextEvents = []
+
+          // If there are more markers in the opening, add them before.
+          if (events[open][1].end.offset - events[open][1].start.offset) {
+            nextEvents = chunkedPush(nextEvents, [
+              ['enter', events[open][1], context],
+              ['exit', events[open][1], context]
+            ])
+          }
+
+          // Opening.
+          nextEvents = chunkedPush(nextEvents, [
+            ['enter', group, context],
+            ['enter', openingSequence, context],
+            ['exit', openingSequence, context],
+            ['enter', text, context]
+          ])
+
+          // Between.
+          nextEvents = chunkedPush(
+            nextEvents,
+            resolveAll(
+              context.parser.constructs.insideSpan.null,
+              events.slice(open + 1, index),
+              context
+            )
+          )
+
+          // Closing.
+          nextEvents = chunkedPush(nextEvents, [
+            ['exit', text, context],
+            ['enter', closingSequence, context],
+            ['exit', closingSequence, context],
+            ['exit', group, context]
+          ])
+
+          // If there are more markers in the closing, add them after.
+          if (events[index][1].end.offset - events[index][1].start.offset) {
+            offset = 2
+            nextEvents = chunkedPush(nextEvents, [
+              ['enter', events[index][1], context],
+              ['exit', events[index][1], context]
+            ])
+          } else {
+            offset = 0
+          }
+
+          chunkedSplice(events, open - 1, index - open + 3, nextEvents)
+
+          index = open + nextEvents.length - offset - 2
+          break
+        }
+      }
+    }
+  }
+
+  // Remove remaining sequences.
+  index = -1
+
+  while (++index < events.length) {
+    if (events[index][1].type === 'attentionSequence') {
+      events[index][1].type = 'data'
+    }
+  }
+
+  return events
+}
+
+function tokenizeAttention(effects, ok) {
+  var before = classifyCharacter(this.previous)
+  var marker
+
+  return start
+
+  function start(code) {
+    assert__default['default'](
+      code === codes.asterisk || code === codes.underscore,
+      'expected asterisk or underscore'
+    )
+    effects.enter('attentionSequence')
+    marker = code
+    return sequence(code)
+  }
+
+  function sequence(code) {
+    var token
+    var after
+    var open
+    var close
+
+    if (code === marker) {
+      effects.consume(code)
+      return sequence
+    }
+
+    token = effects.exit('attentionSequence')
+    after = classifyCharacter(code)
+    open = !after || (after === constants.characterGroupPunctuation && before)
+    close = !before || (before === constants.characterGroupPunctuation && after)
+    token._open = marker === codes.asterisk ? open : open && (before || !close)
+    token._close = marker === codes.asterisk ? close : close && (after || !open)
+    return ok(code)
+  }
+}
+
+module.exports = attention