Old font command support: \rm, \sf, \tt, \bf, \it (#675)

Squashed:
* \rm, \sf, \tt, \bf, \it support
* Fix space consumption after macros without arguments
* Add tests for old font commands

src/Parser.js

@@ -394,6 +394,17 @@ const styleFuncs = [
     "\\displaystyle", "\\textstyle", "\\scriptstyle", "\\scriptscriptstyle",
 ];
 
+// Old font functions
+const oldFontFuncs = {
+    "\\rm": "mathrm",
+    "\\sf": "mathsf",
+    "\\tt": "mathtt",
+    "\\bf": "mathbf",
+    "\\it": "mathit",
+    //"\\sl": "textsl",
+    //"\\sc": "textsc",
+};
+
 /**
  * Parses an implicit group, which is a group that starts at the end of a
  * specified, and ends right before a higher explicit group ends, or at EOL. It
@@ -462,7 +473,8 @@ Parser.prototype.parseImplicitGroup = function() {
         result.position = end.position;
         return result;
     } else if (utils.contains(sizeFuncs, func)) {
-        // If we see a sizing function, parse out the implict body
+        // If we see a sizing function, parse out the implicit body
+        this.consumeSpaces();
         const body = this.parseExpression(false);
         return new ParseNode("sizing", {
             // Figure out what size to use based on the list of functions above
@@ -470,7 +482,8 @@ Parser.prototype.parseImplicitGroup = function() {
             value: body,
         }, this.mode);
     } else if (utils.contains(styleFuncs, func)) {
-        // If we see a styling function, parse out the implict body
+        // If we see a styling function, parse out the implicit body
+        this.consumeSpaces();
         const body = this.parseExpression(true);
         return new ParseNode("styling", {
             // Figure out what style to use by pulling out the style from
@@ -478,6 +491,22 @@ Parser.prototype.parseImplicitGroup = function() {
             style: func.slice(1, func.length - 5),
             value: body,
         }, this.mode);
+    } else if (func in oldFontFuncs) {
+        const style = oldFontFuncs[func];
+        // If we see an old font function, parse out the implicit body
+        this.consumeSpaces();
+        const body = this.parseExpression(true);
+        if (style.slice(0, 4) === 'text') {
+            return new ParseNode("text", {
+                style: style,
+                body: new ParseNode("ordgroup", body, this.mode),
+            }, this.mode);
+        } else {
+            return new ParseNode("font", {
+                font: style,
+                body: new ParseNode("ordgroup", body, this.mode),
+            }, this.mode);
+        }
     } else {
         // Defer to parseFunction if it's not a function we handle
         return this.parseFunction(start);
@@ -629,9 +658,7 @@ Parser.prototype.parseGroupOfType = function(innerMode, optional) {
     if (innerMode === "text") {
         // text mode is special because it should ignore the whitespace before
         // it
-        while (this.nextToken.text === " ") {
-            this.consume();
-        }
+        this.consumeSpaces();
     }
     // By the time we get here, innerMode is one of "text" or "math".
     // We switch the mode of the parser, recurse, then restore the old mode.
@@ -640,6 +667,12 @@ Parser.prototype.parseGroupOfType = function(innerMode, optional) {
     return res;
 };
 
+Parser.prototype.consumeSpaces = function() {
+    while (this.nextToken.text === " ") {
+        this.consume();
+    }
+};
+
 /**
  * Parses a group, essentially returning the string formed by the
  * brace-enclosed tokens plus some position information.

src/functions.js

@@ -591,6 +591,11 @@ defineFunction([
     "\\scriptscriptstyle",
 ], 0, null);
 
+// Old font changing functions
+defineFunction([
+    "\\rm", "\\sf", "\\tt", "\\bf", "\\it", //"\\sl", "\\sc",
+], 0, null);
+
 defineFunction([
     // styles
     "\\mathrm", "\\mathit", "\\mathbf",

test/screenshotter/ss_data.yaml

@@ -118,6 +118,12 @@ NestedFractions: |
     \dfrac{\frac{a}{b}}{\frac{c}{d}}\dfrac{\dfrac{a}{b}}
     {\dfrac{c}{d}}\frac{\frac{a}{b}}{\frac{c}{d}}
 NullDelimiterInteraction: a \bigl. + 2 \quad \left. + a \right)
+OldFont: |
+    \begin{matrix}
+      \rm rm & it & \it it & \bf bf & \sf sf & \tt tt \\
+      \text{\rm rm} & \text{rm} & \text{\it it} & \text{\bf bf} & \text{\sf sf} & \text{\tt tt} \\
+      i\rm r\it i & \text{r\it i\rm r}
+    \end{matrix}
 OpLimits: |
     {\sin_2^2 \lim_2^2 \int_2^2 \sum_2^2}
     {\displaystyle \lim_2^2 \int_2^2 \intop_2^2 \sum_2^2}