From 9ecb67ec22458cb33c5a1067ed1d34b99e2efff0 Mon Sep 17 00:00:00 2001
From: "Davide P. Cervone" <dpvc@union.edu>
Date: Tue, 2 Sep 2014 10:26:45 -0400
Subject: [PATCH] Add minimal support for \hfill (just to handle column
 alignment in matrices and arrays).  Issue #903.

---
 unpacked/jax/input/TeX/jax.js | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/unpacked/jax/input/TeX/jax.js b/unpacked/jax/input/TeX/jax.js
index fffaad2a3..359cbb49f 100644
--- a/unpacked/jax/input/TeX/jax.js
+++ b/unpacked/jax/input/TeX/jax.js
@@ -258,7 +258,7 @@
   STACKITEM.array = STACKITEM.Subclass({
     type: "array", isOpen: true, arraydef: {},
     Init: function () {
-      this.table = []; this.row = []; this.env = {}; this.frame = []
+      this.table = []; this.row = []; this.env = {}; this.frame = []; this.hfill = [];
       this.SUPER(arguments).Init.apply(this,arguments);
     },
     checkItem: function (item) {
@@ -286,7 +286,15 @@
       }
       return this.SUPER(arguments).checkItem.call(this,item);
     },
-    EndEntry: function () {this.row.push(MML.mtd.apply(MML,this.data)); this.data = []},
+    EndEntry: function () {
+      var mtd = MML.mtd.apply(MML,this.data);
+      if (this.hfill.length) {
+        if (this.hfill[0] === 0) mtd.columnalign = "right";
+        if (this.hfill[this.hfill.length-1] === this.data.length)
+          mtd.columnalign = (mtd.columnalign ? "center" : "left");
+      }
+      this.row.push(mtd); this.data = []; this.hfill = [];
+    },
     EndRow:   function () {this.table.push(MML.mtr.apply(MML,this.row)); this.row = []},
     EndTable: function () {
       if (this.data.length || this.row.length) {this.EndEntry(); this.EndRow()}
@@ -915,6 +923,9 @@
 //      noalign:            'HandleNoAlign',
         eqalignno:         ['Matrix',null,null,"right left right",MML.LENGTH.THICKMATHSPACE+" 3em",".5em",'D'],
         leqalignno:        ['Matrix',null,null,"right left right",MML.LENGTH.THICKMATHSPACE+" 3em",".5em",'D'],
+        hfill:              'HFill',
+        hfil:               'HFill',   // \hfil treated as \hfill for now
+        hfilll:             'HFill',   // \hfilll treated as \hfill for now
 
         //  TeX substitution macros
         bmod:              ['Macro','\\mmlToken{mo}[lspace="thickmathspace" rspace="thickmathspace"]{mod}'],
@@ -1713,6 +1724,14 @@
       }
     },
     
+    HFill: function (name) {
+      var top = this.stack.Top();
+      if (top.isa(STACKITEM.array)) top.hfill.push(top.data.length);
+        else TEX.Error(["UnsupportedHFill","Unsupported use of %1",name]);
+    },
+    
+
+    
    /************************************************************************/
    /*
     *   LaTeX environments