Merge pull request #710 from mathjax/nonscript

Add \noscript command

Author: dpvc

ts/input/tex/base/BaseConfiguration.ts

@@ -32,6 +32,8 @@ import * as bitem from './BaseItems.js';
 import {AbstractTags} from '../Tags.js';
 import './BaseMappings.js';
 import {getRange} from '../../../core/MmlTree/OperatorDictionary.js';
+import {MmlNode} from '../../../core/MmlTree/MmlNode.js';
+import ParseOptions from '../ParseOptions.js';
 
 /**
  * Remapping some ASCII characters to their Unicode operator equivalent.
@@ -89,6 +91,45 @@ function envUndefined(_parser: TexParser, env: string) {
   throw new TexError('UnknownEnv', 'Unknown environment \'%1\'', env);
 }
 
+/**
+ * Filter for removing spacing following \nonscript
+ * @param{ParseOptions} data The active tex parser.
+ */
+function filterNonscript({data}: {data: ParseOptions}) {
+  for (const mml of data.getList('nonscript')) {
+    //
+    //  This is the list of mspace elements or mrow > mstyle > mspace
+    //    that followed \nonscript macros to be tested for removal.
+    //
+    if (mml.attributes.get('scriptlevel') > 0) {
+      //
+      //  The mspace needs to be removed, since we are in a script style.
+      //  Remove it from the DOM and from the list of mspace elements.
+      //
+      const parent = mml.parent;
+      parent.childNodes.splice(parent.childIndex(mml), 1);
+      data.removeFromList(mml.kind, [mml]);
+      //
+      //  If it is an mrow > mstyle > mspace, then we have just
+      //    removed the mrow from its list, and must remove
+      //    the mstyle and mspace from their lists as well.
+      //
+      if (mml.isKind('mrow')) {
+        const mstyle = mml.childNodes[0] as MmlNode;
+        data.removeFromList('mstyle', [mstyle]);
+        data.removeFromList('mspace', mstyle.childNodes[0].childNodes as MmlNode[]);
+      }
+    } else if (mml.isKind('mrow')) {
+      //
+      // This is an mrow > mstyle > mspace  but we're not in a script
+      //   style, so remove the mrow that we had added in the NonscriptItem.
+      //
+      mml.parent.replaceChild(mml.childNodes[0], mml);
+      data.removeFromList('mrow', [mml]);
+    }
+  }
+}
+
 
 /**
  * @constructor
@@ -135,19 +176,21 @@ export const BaseConfiguration: Configuration = Configuration.create(
       [bitem.MmlItem.prototype.kind]: bitem.MmlItem,
       [bitem.FnItem.prototype.kind]: bitem.FnItem,
       [bitem.NotItem.prototype.kind]: bitem.NotItem,
+      [bitem.NonscriptItem.prototype.kind]: bitem.NonscriptItem,
       [bitem.DotsItem.prototype.kind]: bitem.DotsItem,
       [bitem.ArrayItem.prototype.kind]: bitem.ArrayItem,
       [bitem.EqnArrayItem.prototype.kind]: bitem.EqnArrayItem,
       [bitem.EquationItem.prototype.kind]: bitem.EquationItem
-     },
-     options: {
-       maxMacros: 1000,
-       baseURL: (typeof(document) === 'undefined' ||
-                 document.getElementsByTagName('base').length === 0) ?
-             '' : String(document.location).replace(/#.*$/, '')
-     },
-     tags: {
-       base: BaseTags
-     }
+    },
+    options: {
+      maxMacros: 1000,
+      baseURL: (typeof(document) === 'undefined' ||
+                document.getElementsByTagName('base').length === 0) ?
+                '' : String(document.location).replace(/#.*$/, '')
+    },
+    tags: {
+      base: BaseTags
+    },
+    postprocessors: [[filterNonscript, -4]]
   }
 );

ts/input/tex/base/BaseItems.ts

@@ -773,6 +773,53 @@ export class NotItem extends BaseItem {
   }
 }
 
+/**
+ * A StackItem that removes an mspace that follows it (for \nonscript).
+ */
+export class NonscriptItem extends BaseItem {
+
+  /**
+   * @override
+   */
+  public get kind() {
+    return 'nonscript';
+  }
+
+  /**
+   * @override
+   */
+  public checkItem(item: StackItem): CheckType {
+    //
+    //  Check if the next item is an mspace (or an mspace in an mstyle) and remove it.
+    //
+    if (item.isKind('mml') && item.Size() === 1) {
+      let mml = item.First;
+      //
+      //  Space macros like \, are wrapped with an mstyle to set scriptlevel="0"
+      //    (so size is independent of level), we look at the contents of the mstyle for the mspace.
+      //
+      if (mml.isKind('mstyle') && mml.notParent) {
+        mml = NodeUtil.getChildren(NodeUtil.getChildren(mml)[0])[0];
+      }
+      if (mml.isKind('mspace')) {
+        //
+        //  If the space is in an mstyle, wrap it in an mrow so we can test its scriptlevel
+        //    in the post-filter (the mrow will be removed in the filter).  We can't test
+        //    the mstyle's scriptlevel, since it is ecxplicitly setting it to 0.
+        //
+        if (mml !== item.First) {
+          const mrow = this.create('node', 'mrow', [item.Pop()]);
+          item.Push(mrow);
+        }
+        //
+        //  Save the mspace for later post-processing.
+        //
+        this.factory.configuration.addNode('nonscript', item.First);
+      }
+    }
+    return [[item], true];
+  }
+}
 
 /**
  * Item indicating a dots command has been encountered.

ts/input/tex/base/BaseMappings.ts

@@ -575,6 +575,7 @@ new sm.CommandMap('macros', {
   rule:               'rule',
   Rule:              ['Rule'],
   Space:             ['Rule', 'blank'],
+  nonscript:          'Nonscript',
 
   big:               ['MakeBig', TEXCLASS.ORD, 0.85],
   Big:               ['MakeBig', TEXCLASS.ORD, 1.15],

ts/input/tex/base/BaseMethods.ts

@@ -896,6 +896,16 @@ BaseMethods.Hskip = function(parser: TexParser, name: string) {
 };
 
 
+/**
+ * Handle removal of spaces in script modes
+ * @param {TexParser} parser The calling parser.
+ * @param {string} name The macro name.
+ */
+BaseMethods.Nonscript = function(parser: TexParser, _name: string) {
+  parser.Push(parser.itemFactory.create('nonscript'));
+};
+
+
 /**
  * Handle Rule and Space command
  * @param {TexParser} parser The calling parser.