Rewrites error messages in stack items into a static object.

Author: zorkow

mathjax3-ts/input/tex/StackItem.ts

@@ -341,7 +341,7 @@ export abstract class BaseItem extends MmlStack implements StackItem {
    * A list of basic errors.
    * @type {{[key: string]: string[]}}
    */
-  protected errors: {[key: string]: string[]} = {
+  protected static errors: {[key: string]: string[]} = {
     // @test ExtraOpenMissingClose
     end: ['MissingBeginExtraEnd', 'Missing \\begin{%1} or extra \\end{%1}'],
     // @test ExtraCloseMissingOpen
@@ -452,10 +452,10 @@ export abstract class BaseItem extends MmlStack implements StackItem {
       // @test Ampersand-error
       throw new TexError('Misplaced', 'Misplaced %1', item.getName());
     }
-    if (item.isClose && this.errors[item.kind]) {
+    if (item.isClose && this.getErrors(item.kind)) {
       // @test ExtraOpenMissingClose, ExtraCloseMissingOpen,
       //       MissingLeftExtraRight, MissingBeginExtraEnd
-      const [id, message] = this.errors[item.kind];
+      const [id, message] = this.getErrors(item.kind);
       throw new TexError(id, message, item.getName());
     }
     if (!item.isFinal) {
@@ -500,4 +500,17 @@ export abstract class BaseItem extends MmlStack implements StackItem {
     return this.kind + '[' + this.nodes.join('; ') + ']';
   }
 
+
+  /**
+   * Get error messages for a particular types of stack items. This reads error
+   * messages from the static errors object, which can be extended in
+   * subclasses.
+   * @param {string} kind The stack item type.
+   * @return {string[]} The list of arguments for the TeXError.
+   */
+  public getErrors(kind: string): string[] {
+    const CLASS = (this.constructor as typeof BaseItem);
+    return (CLASS.errors || {})[kind] || BaseItem.errors[kind];
+  }
+
 }

mathjax3-ts/input/tex/TexParser.ts

@@ -179,7 +179,8 @@ export default class TexParser {
    * Parses the current input string.
    */
   public Parse() {
-    let c, n;
+    let c: string;
+    let n: number;
     while (this.i < this.string.length) {
       c = this.string.charAt(this.i++);
       n = c.charCodeAt(0);

mathjax3-ts/input/tex/base/BaseItems.ts

@@ -112,15 +112,15 @@ export class StopItem extends BaseItem {
  */
 export class OpenItem extends BaseItem {
 
+
   /**
    * @override
    */
-  constructor(factory: StackItemFactory) {
-    super(factory);
+  protected static errors = Object.assign(Object.create(BaseItem.errors), {
     // @test ExtraOpenMissingClose
-    this.errors['stop'] = ['ExtraOpenMissingClose',
-                           'Extra open brace or missing close brace'];
-  }
+    'stop': ['ExtraOpenMissingClose',
+             'Extra open brace or missing close brace']
+  });
 
   /**
    * @override
@@ -212,18 +212,17 @@ export class SubsupItem extends BaseItem {
   /**
    * @override
    */
-  constructor(factory: StackItemFactory, ...nodes: MmlNode[]) {
-    super(factory, ...nodes);
+  protected static errors = Object.assign(Object.create(BaseItem.errors), {
     // @test MissingScript Sub, MissingScript Sup
-    this.errors['stop'] = ['MissingScript',
-                           'Missing superscript or subscript argument'];
+    'stop': ['MissingScript',
+             'Missing superscript or subscript argument'],
     // @test MissingOpenForSup
-    this.errors['sup'] =  ['MissingOpenForSup',
-                           'Missing open brace for superscript'];
+    'sup': ['MissingOpenForSup',
+            'Missing open brace for superscript'],
     // @test MissingOpenForSub
-    this.errors['sub'] =  ['MissingOpenForSub',
-                           'Missing open brace for subscript'];
-  }
+    'sub': ['MissingOpenForSub',
+            'Missing open brace for subscript']
+  });
 
   /**
    * @override
@@ -263,7 +262,7 @@ export class SubsupItem extends BaseItem {
     }
     if (super.checkItem(item)[1]) {
       // @test Brace Superscript Error, MissingOpenForSup, MissingOpenForSub
-      const error = this.errors[['', 'sub', 'sup'][position]];
+      const error = this.getErrors(['', 'sub', 'sup'][position]);
       throw new TexError(error[0], error[1], ...error.splice(2));
     }
   }
@@ -347,15 +346,22 @@ export class OverItem extends BaseItem {
  */
 export class LeftItem extends BaseItem {
 
+  /**
+   * @override
+   */
+  protected static errors = Object.assign(Object.create(BaseItem.errors), {
+    // @test ExtraLeftMissingRight
+    'stop': ['ExtraLeftMissingRight',
+             'Extra \\left or missing \\right']
+  });
+
+
   /**
    * @override
    */
   constructor(factory: StackItemFactory) {
     super(factory);
-    this.setProperty('delim', '('),
-    // @test ExtraLeftMissingRight
-    this.errors['stop'] = ['ExtraLeftMissingRight',
-                           'Extra \\left or missing \\right'];
+    this.setProperty('delim', '(');
   }
 
   /**