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AutoLaTeX/MathJax/extensions/TeX/begingroup.js

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+/* -*- Mode: Javascript; indent-tabs-mode:nil; js-indent-level: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+
+/*************************************************************
+ *
+ *  MathJax/extensions/TeX/begingroup.js
+ *  
+ *  Implements \begingroup and \endgroup commands that make local 
+ *  definitions possible and are removed when the \endgroup occurs.  
+ *
+ *  ---------------------------------------------------------------------
+ *  
+ *  Copyright (c) 2011-2017 The MathJax Consortium
+ * 
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+MathJax.Extension["TeX/begingroup"] = {
+  version: "2.7.2"
+};
+
+MathJax.Hub.Register.StartupHook("TeX Jax Ready",function () {
+
+  var TEX = MathJax.InputJax.TeX,
+      TEXDEF = TEX.Definitions;
+
+  /****************************************************/
+
+  //
+  //  A namespace for localizing macros and environments
+  //  (\begingroup and \endgroup create and destroy these)
+  //
+  var NSFRAME = MathJax.Object.Subclass({
+    macros: null,         // the local macro definitions
+    environments: null,   // the local environments
+    Init: function (macros,environments) {
+      this.macros = (macros || {});
+      this.environments = (environments || {});
+    },
+    //
+    //  Find a macro or environment by name
+    //
+    Find: function (name,type) {if (this[type][name]) {return this[type][name]}},
+    //
+    //  Define or remove a macro or environment
+    //
+    Def: function (name,value,type) {this[type][name] = value},
+    Undef: function (name,type) {delete this[type][name]},
+    //
+    //  Merge two namespaces (used when the equation namespace is combined with the root one)
+    //
+    Merge: function (frame) {
+      MathJax.Hub.Insert(this.macros,frame.macros);
+      MathJax.Hub.Insert(this.environments,frame.environments);
+    },
+    //
+    //  Move global macros to the stack (globally) and remove from the frame
+    //
+    MergeGlobals: function (stack) {
+      var macros = this.macros;
+      for (var cs in macros) {if (macros.hasOwnProperty(cs) && macros[cs].global) {
+        stack.Def(cs,macros[cs],"macros",true);
+        delete macros[cs].global; delete macros[cs];
+      }}
+    },
+    //
+    //  Clear the macro and environment lists
+    //  (but not global macros unless "all" is true)
+    //
+    Clear: function (all) {
+      this.environments = {};
+      if (all) {this.macros = {}} else {
+        var macros = this.macros;
+        for (var cs in macros) {
+          if (macros.hasOwnProperty(cs) && !macros[cs].global) {delete macros[cs]}
+        }
+      }
+      return this;
+    }
+  });
+
+  /****************************************************/
+
+  //
+  //  A Stack of namespace frames
+  //
+  var NSSTACK = TEX.nsStack = MathJax.Object.Subclass({
+    stack: null,         // the namespace frames
+    top: 0,              // the current top one (we don't pop for real until the equation completes)
+    isEqn: false,        // true if this is the equation stack (not the global one)
+    //
+    //  Set up the initial stack frame
+    //
+    Init: function (eqn) {
+      this.isEqn = eqn; this.stack = [];
+      if (!eqn) {this.Push(NSFRAME(TEXDEF.macros,TEXDEF.environment))}
+           else {this.Push(NSFRAME())}
+    },
+    //
+    //  Define a macro or environment in the top frame
+    //
+    Def: function (name,value,type,global) {
+      var n = this.top-1;
+      if (global) {
+        //
+        //  Define global macros in the base frame and remove that cs
+        //  from all other frames.  Mark the global ones in equations
+        //  so they can be made global when merged with the root stack.
+        //
+        while (n > 0) {this.stack[n].Undef(name,type); n--}
+        if (!MathJax.Object.isArray(value)) {value = [value]}
+        if (this.isEqn) {value.global = true}
+      }
+      this.stack[n].Def(name,value,type);
+    },
+    //
+    //  Push a new namespace frame on the stack
+    //
+    Push: function (frame) {
+      this.stack.push(frame);
+      this.top = this.stack.length;
+    },
+    //
+    //  Pop the top stack frame
+    //  (if it is the root, just keep track of the pop so we can
+    //   reset it if the equation is reprocessed)
+    //
+    Pop: function () {
+      var top;
+      if (this.top > 1) {
+        top = this.stack[--this.top];
+        if (this.isEqn) {this.stack.pop()}
+      } else if (this.isEqn) {
+        this.Clear();
+      }
+      return top;
+    },
+    //
+    //  Search the stack from top to bottom for the first
+    //    definition of the given control sequence in the given type
+    //
+    Find: function (name,type) {
+      for (var i = this.top-1; i >= 0; i--) {
+        var def = this.stack[i].Find(name,type);
+        if (def) {return def}
+      }
+      return null;
+    },
+    //
+    //  Combine the equation stack with the global one
+    //  (The bottom frame of the equation goes with the top frame of the global one,
+    //   and the remainder are pushed on the global stack, truncated to the
+    //   position where items were poped from it.)
+    //
+    Merge: function (stack) {
+      stack.stack[0].MergeGlobals(this);
+      this.stack[this.top-1].Merge(stack.stack[0]);
+      var data = [this.top,this.stack.length-this.top].concat(stack.stack.slice(1));
+      this.stack.splice.apply(this.stack,data);
+      this.top = this.stack.length;
+    },
+    //
+    //  Put back the temporarily poped items
+    //
+    Reset: function () {this.top = this.stack.length},
+    //
+    //  Clear the stack and start with a blank frame
+    //
+    Clear: function (all) {
+      this.stack = [this.stack[0].Clear()];
+      this.top = this.stack.length;
+    }
+  },{
+    nsFrame: NSFRAME
+  });
+
+  /****************************************************/
+
+  //
+  //  Define the new macros
+  //
+  TEXDEF.Add({
+    macros: {
+      begingroup: "BeginGroup",
+      endgroup:   "EndGroup",
+      global:     ["Extension","newcommand"],
+      gdef:       ["Extension","newcommand"]
+    }
+  },null,true);
+  
+  TEX.Parse.Augment({
+    //
+    //  Implement \begingroup
+    //
+    BeginGroup: function (name) {
+      TEX.eqnStack.Push(NSFRAME());
+    },
+    //
+    //  Implements \endgroup
+    //
+    EndGroup: function (name) {
+      //
+      //  If the equation has pushed frames, pop one,
+      //  Otherwise clear the equation stack and pop the top global one
+      //
+      if (TEX.eqnStack.top > 1) {
+        TEX.eqnStack.Pop();
+      } else if (TEX.rootStack.top === 1) {
+        TEX.Error(["ExtraEndMissingBegin","Extra %1 or missing \\begingroup",name]);
+      } else {
+        TEX.eqnStack.Clear();
+        TEX.rootStack.Pop();
+      }
+    },
+
+    //
+    //  Replace the original routines with ones that looks through the
+    //  equation and root stacks for the given name
+    //  
+    csFindMacro: function (name) {
+      return (TEX.eqnStack.Find(name,"macros") || TEX.rootStack.Find(name,"macros"));
+    },
+    envFindName: function (name) {
+      return (TEX.eqnStack.Find(name,"environments") || TEX.rootStack.Find(name,"environments"));
+    }
+
+  });
+
+  /****************************************************/
+
+  TEX.rootStack = NSSTACK();         // the global namespace stack
+  TEX.eqnStack  = NSSTACK(true);     // the equation stack
+
+  //
+  //  Reset the global stack and clear the equation stack
+  //  (this gets us back to the initial stack state as it was
+  //   before the equation was first processed, in case the equation
+  //   get restarted due to an autoloaded file)
+  //
+  TEX.prefilterHooks.Add(function () {TEX.rootStack.Reset(); TEX.eqnStack.Clear(true)});
+  
+  //
+  //  We only get here if there were no errors and the equation is fully
+  //  processed (all restarts are complete).  So we merge the equation
+  //  stack into the global stack, thus making the changes from this
+  //  equation permanent.
+  //
+  TEX.postfilterHooks.Add(function () {TEX.rootStack.Merge(TEX.eqnStack)});
+  
+  /*********************************************************/
+
+  MathJax.Hub.Register.StartupHook("TeX newcommand Ready",function () {
+
+    //
+    //  Add the commands that depend on the newcommand code
+    //
+    TEXDEF.Add({
+      macros: {
+        global: "Global",
+        gdef:   ["Macro","\\global\\def"]
+      }
+    },null,true);
+
+    TEX.Parse.Augment({
+      //
+      //  Modify the way macros and environments are defined
+      //  to make them go into the equation namespace stack
+      //
+      setDef: function (name,value) {
+        value.isUser = true;
+        TEX.eqnStack.Def(name,value,"macros",this.stack.env.isGlobal);
+        delete this.stack.env.isGlobal;
+      },
+      setEnv: function (name,value) {
+        value.isUser = true;
+        TEX.eqnStack.Def(name,value,"environments")
+      },
+
+      //
+      //  Implement \global (for \global\let, \global\def and \global\newcommand)
+      //
+      Global: function (name) {
+        var i = this.i; var cs = this.GetCSname(name); this.i = i;
+        if (cs !== "let" && cs !== "def" && cs !== "newcommand") {
+          TEX.Error(["GlobalNotFollowedBy",
+                     "%1 not followed by \\let, \\def, or \\newcommand",name]);
+        }
+        this.stack.env.isGlobal = true;
+      }
+
+    });
+
+  });
+
+  MathJax.Hub.Startup.signal.Post("TeX begingroup Ready");
+
+});
+
+MathJax.Ajax.loadComplete("[MathJax]/extensions/TeX/begingroup.js");