Added proper math-mode escaping

index.js

@@ -40,39 +40,36 @@ function isValidDelim(state, pos) {
 }
 
 function math_inline(state, silent) {
-    var start, match, token, res,
-        pos = state.pos;
+    var start, match, token, res, pos, esc_count;
 
     if (state.src[state.pos] !== "$") { return false; }
 
-    res = isValidDelim(state, pos);
+    res = isValidDelim(state, state.pos);
     if (!res.can_open) {
         if (!silent) { state.pending += "$"; }
         state.pos += 1;
         return true;
     }
 
+    // First check for and bypass all properly escaped delimieters
+    // This loop will assume that the first leading backtick can not
+    // be the first character in state.src, which is known since
+    // we have found an opening delimieter already.
     start = state.pos + 1;
-    match = state.src.indexOf("$", start);
+    match = start;
+    while ( (match = state.src.indexOf("$", match)) !== -1) {
+        // Found potential $, look for escapes, pos will point to
+        // first non escape when complete
+        pos = match - 1;
+        while (state.src[pos] === "\\") { pos -= 1; }
 
-    // No closing delimter found.  Consume $ and continue.
-    if (match === -1) {
-        if (!silent) { state.pending += "$"; }
-        state.pos = start;
-        return true;
+        // Even number of escapes, potential closing delimiter found
+        if ( ((match - pos) % 2) == 1 ) { break; }
+        match += 1;
     }
 
-    res = isValidDelim(state, match);
-
-    // We only will look at the very next delimeter while searching
-    // for closing delimeters.  As a consequnce, we will never send
-    // KaTeX a $ inside of math mode, even if escaped.  The other alternative
-    // would otherwise require escaping commonly used things such as
-    // \int, \sum, etc...  Perhaps there is a way to find a better solution.
-    // Such as counting the number of \\\\\\\$ and if odd escape $ and remove
-    // and leading \ or otherwise leave as is.
-
-    if (!res.can_close) {
+    // No closing delimter found.  Consume $ and continue.
+    if (match === -1) {
         if (!silent) { state.pending += "$"; }
         state.pos = start;
         return true;
@@ -85,6 +82,14 @@ function math_inline(state, silent) {
         return true;
     }
 
+    // Check for valid closing delimiter
+    res = isValidDelim(state, match);
+    if (!res.can_close) {
+        if (!silent) { state.pending += "$"; }
+        state.pos = start;
+        return true;
+    }
+
     if (!silent) {
         token         = state.push('math_inline', 'math', 0);
         token.markup  = "$";

test/fixtures/default.txt

@@ -207,3 +207,17 @@ It's well know that $$1 + 1 = 3$$ for sufficiently large 1.
 .
 <p>It's well know that $$1 + 1 = 3$$ for sufficiently large 1.</p>
 .
+
+Escaped delimiters in math mode
+.
+Money adds: $\$X + \$Y = \$Z$.
+.
+<p>Money adds: <span class="katex"><span class="katex-mathml"><math><semantics><mrow><mi mathvariant="normal">$</mi><mi>X</mi><mo>+</mo><mi mathvariant="normal">$</mi><mi>Y</mi><mo>=</mo><mi mathvariant="normal">$</mi><mi>Z</mi></mrow><annotation encoding="application/x-tex">\$X + \$Y = \$Z</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="strut" style="height:0.75em;"></span><span class="strut bottom" style="height:0.83333em;vertical-align:-0.08333em;"></span><span class="base textstyle uncramped"><span class="mord mathrm">$</span><span class="mord mathit" style="margin-right:0.07847em;">X</span><span class="mbin">+</span><span class="mord mathrm">$</span><span class="mord mathit" style="margin-right:0.22222em;">Y</span><span class="mrel">=</span><span class="mord mathrm">$</span><span class="mord mathit" style="margin-right:0.07153em;">Z</span></span></span></span>.</p>
+.
+
+Multiple escaped delimiters in math module
+.
+Weird-o: $\displaystyle{\begin{pmatrix} \$ & 1\\\$ \end{pmatrix}}$.
+.
+<p>Weird-o: <span class="katex"><span class="katex-mathml"><math><semantics><mrow><mstyle scriptlevel="0" displaystyle="true"><mrow><mrow><mo fence="true">(</mo><mtable><mtr><mtd><mrow><mi mathvariant="normal">$</mi></mrow></mtd><mtd><mrow><mn>1</mn></mrow></mtd></mtr><mtr><mtd><mrow><mi mathvariant="normal">$</mi></mrow></mtd></mtr></mtable><mo fence="true">)</mo></mrow></mrow></mstyle></mrow><annotation encoding="application/x-tex">\displaystyle{\begin{pmatrix} \$ &amp; 1\\\$ \end{pmatrix}}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="strut" style="height:1.45em;"></span><span class="strut bottom" style="height:2.40003em;vertical-align:-0.95003em;"></span><span class="base textstyle uncramped"><span class="reset-textstyle displaystyle textstyle uncramped"><span class="mord displaystyle textstyle uncramped"><span class="minner displaystyle textstyle uncramped"><span class="style-wrap reset-textstyle textstyle uncramped" style="top:0em;"><span class="delimsizing size3">(</span></span><span class="mord"><span class="mtable"><span class="col-align-c"><span class="vlist"><span style="top:-0.6099999999999999em;"><span class="fontsize-ensurer reset-size5 size5"><span style="font-size:0em;">​</span></span><span class="mord displaystyle textstyle uncramped"><span class="mord mathrm">$</span></span></span><span style="top:0.5900000000000003em;"><span class="fontsize-ensurer reset-size5 size5"><span style="font-size:0em;">​</span></span><span class="mord displaystyle textstyle uncramped"><span class="mord mathrm">$</span></span></span><span class="baseline-fix"><span class="fontsize-ensurer reset-size5 size5"><span style="font-size:0em;">​</span></span>​</span></span></span><span class="arraycolsep" style="width:0.5em;"></span><span class="arraycolsep" style="width:0.5em;"></span><span class="col-align-c"><span class="vlist"><span style="top:-0.6099999999999999em;"><span class="fontsize-ensurer reset-size5 size5"><span style="font-size:0em;">​</span></span><span class="mord displaystyle textstyle uncramped"><span class="mord mathrm">1</span></span></span><span class="baseline-fix"><span class="fontsize-ensurer reset-size5 size5"><span style="font-size:0em;">​</span></span>​</span></span></span></span></span><span class="style-wrap reset-textstyle textstyle uncramped" style="top:0em;"><span class="delimsizing size3">)</span></span></span></span></span></span></span></span>.</p>
+.