Implement correct macros for liminf and limsup, fixes #111 (#887)

* Implement correct macros for liminf and limsup, fixes #111

* fix nits

src/buildMathML.js

@@ -198,9 +198,19 @@ groupTypes.supsub = function(group, options) {
     if (isBrace) {
         nodeType = (isOver ? "mover" : "munder");
     } else if (!group.value.sub) {
-        nodeType = "msup";
+        const base = group.value.base;
+        if (base && base.value.limits && options.style === Style.DISPLAY) {
+            nodeType = "mover";
+        } else {
+            nodeType = "msup";
+        }
     } else if (!group.value.sup) {
-        nodeType = "msub";
+        const base = group.value.base;
+        if (base && base.value.limits && options.style === Style.DISPLAY) {
+            nodeType = "munder";
+        } else {
+            nodeType = "msub";
+        }
     } else {
         const base = group.value.base;
         if (base && base.value.limits && options.style === Style.DISPLAY) {

src/functions.js

@@ -181,8 +181,7 @@ defineFunction([
 
 // Limits, not symbols
 defineFunction([
-    "\\det", "\\gcd", "\\inf", "\\lim", "\\liminf", "\\limsup", "\\max",
-    "\\min", "\\Pr", "\\sup",
+    "\\det", "\\gcd", "\\inf", "\\lim", "\\max", "\\min", "\\Pr", "\\sup",
 ], {
     numArgs: 0,
 }, function(context) {

src/functions/operatorname.js

@@ -30,22 +30,27 @@ defineFunction({
             let mode = "";
 
             // Consolidate Greek letter function names into symbol characters.
-            const temp = html.buildExpression(group.value.value, options, true);
+            const temp = html.buildExpression(
+                group.value.value, options.withFontFamily("mathrm"), true);
 
             // All we want from temp are the letters. With them, we'll
             // create a text operator similar to \tan or \cos.
-            for (let i = 0; i < temp.length; i++) {
-                letter = temp[i].value;
+            for (const child of temp) {
+                if (child instanceof domTree.symbolNode) {
+                    letter = child.value;
 
-                // In the amsopn package, \newmcodes@ changes four
-                // characters, *-/:’, from math operators back into text.
-                // Given what is in temp, we have to address two of them.
-                letter = letter.replace(/\u2212/, "-");   // minus => hyphen
-                letter = letter.replace(/\u2217/, "*");
+                    // In the amsopn package, \newmcodes@ changes four
+                    // characters, *-/:’, from math operators back into text.
+                    // Given what is in temp, we have to address two of them.
+                    letter = letter.replace(/\u2212/, "-");   // minus => hyphen
+                    letter = letter.replace(/\u2217/, "*");
 
-                // Use math mode for Greek letters
-                mode = (/[\u0391-\u03D7]/.test(letter) ? "math" : "text");
-                output.push(buildCommon.mathsym(letter, mode));
+                    // Use math mode for Greek letters
+                    mode = (/[\u0391-\u03D7]/.test(letter) ? "math" : "text");
+                    output.push(buildCommon.mathsym(letter, mode));
+                } else {
+                    output.push(child);
+                }
             }
         }
         return buildCommon.makeSpan(["mop"], output, options);
@@ -55,12 +60,11 @@ defineFunction({
         // The steps taken here are similar to the html version.
         let output = [];
         if (group.value.value.length > 0) {
-            const temp = mml.buildExpression(group.value.value, options);
+            const temp = mml.buildExpression(
+                group.value.value, options.withFontFamily("mathrm"));
+
+            let word = temp.map(node => node.toText()).join("");
 
-            let word = "";
-            for (let i = 0; i < temp.length; i++) {
-                word += temp[i].children[0].text;
-            }
             word = word.replace(/\u2212/g, "-");
             word = word.replace(/\u2217/g, "*");
             output = [new mathMLTree.TextNode(word)];

src/macros.js

@@ -399,3 +399,5 @@ defineMacro("\\approxcoloncolon",
 //       macro turned into a propper defineSymbol in symbols.js. That way, the
 //       MathML result will be much cleaner.
 defineMacro("\\notni", "\\not\\ni");
+defineMacro("\\limsup", "\\DOTSB\\mathop{\\operatorname{lim\\,sup}}\\limits");
+defineMacro("\\liminf", "\\DOTSB\\mathop{\\operatorname{lim\\,inf}}\\limits");

src/mathMLTree.js

@@ -93,6 +93,22 @@ class MathNode {
 
         return markup;
     }
+
+    /**
+     * Converts the math node into a string, similar to innerText.
+     */
+    toText(): string {
+        if (this.type === "mspace") {
+            if (this.attributes.width === "0.16667em") {
+                return "\u2006";
+            } else {
+                // TODO: Use other space characters for different widths.
+                // https://github.com/Khan/KaTeX/issues/1036
+                return " ";
+            }
+        }
+        return this.children.map(child => child.toText()).join("");
+    }
 }
 
 /**
@@ -118,6 +134,13 @@ class TextNode {
     toMarkup(): string {
         return utils.escape(this.text);
     }
+
+    /**
+     * Converts the text node into a string (which is just the text iteself).
+     */
+    toText(): string {
+        return this.text;
+    }
 }
 
 export default {

static/main.js

@@ -21,7 +21,9 @@ function init() {
     }
 
     var macros = {};
-    var options = {};
+    // TODO: Add toggle for displayMode.
+    // https://github.com/Khan/KaTeX/issues/1035
+    var options = {displayMode: true};
     var macroRegex = /(?:^\?|&)(?:\\|%5[Cc])([A-Za-z]+)=([^&]*)/g;
     var macroString = "";
     while ((match = macroRegex.exec(window.location.search)) !== null) {

test/__snapshots__/mathml-spec.js.snap

@@ -77,6 +77,76 @@ exports[`A MathML builder should make prime operators into <mo> nodes 1`] = `
 
 `;
 
+exports[`A MathML builder should output \\limsup_{x \\rightarrow \\infty} correctly in \\textstyle 1`] = `
+
+<math>
+  <semantics>
+    <mrow>
+      <msub>
+        <mo>
+          <mi mathvariant="normal">
+            lim sup
+          </mi>
+          <mo>
+            ⁡
+          </mo>
+        </mo>
+        <mrow>
+          <mi>
+            x
+          </mi>
+          <mo>
+            →
+          </mo>
+          <mi mathvariant="normal">
+            ∞
+          </mi>
+        </mrow>
+      </msub>
+    </mrow>
+    <annotation encoding="application/x-tex">
+      \\limsup_{x \\rightarrow \\infty}
+    </annotation>
+  </semantics>
+</math>
+
+`;
+
+exports[`A MathML builder should output \\limsup_{x \\rightarrow \\infty} in displaymode correctly 1`] = `
+
+<math>
+  <semantics>
+    <mrow>
+      <munder>
+        <mo>
+          <mi mathvariant="normal">
+            lim sup
+          </mi>
+          <mo>
+            ⁡
+          </mo>
+        </mo>
+        <mrow>
+          <mi>
+            x
+          </mi>
+          <mo>
+            →
+          </mo>
+          <mi mathvariant="normal">
+            ∞
+          </mi>
+        </mrow>
+      </munder>
+    </mrow>
+    <annotation encoding="application/x-tex">
+      \\limsup_{x \\rightarrow \\infty}
+    </annotation>
+  </semantics>
+</math>
+
+`;
+
 exports[`A MathML builder should render boldsymbol with the correct mathvariants 1`] = `
 
 <math>

test/katex-spec.js

@@ -2733,6 +2733,16 @@ describe("A macro expander", function() {
         expect("\\hspace{1em}").toParseLike("\\kern1em");
         expect("\\hspace*{1em}").toParseLike("\\kern1em");
     });
+
+    it("should expand \\limsup as expected", () => {
+        expect("\\limsup")
+            .toParseLike("\\mathop{\\operatorname{lim\\,sup}}\\limits");
+    });
+
+    it("should expand \\liminf as expected", () => {
+        expect("\\liminf")
+            .toParseLike("\\mathop{\\operatorname{lim\\,inf}}\\limits");
+    });
 });
 
 describe("A parser taking String objects", function() {

test/mathml-spec.js

@@ -51,6 +51,19 @@ describe("A MathML builder", function() {
         expect(getMathML("\\textstyle\\sum_a^b")).toMatchSnapshot();
     });
 
+    it("should output \\limsup_{x \\rightarrow \\infty} correctly in " +
+            "\\textstyle", () => {
+        const mathml = getMathML("\\limsup_{x \\rightarrow \\infty}");
+        expect(mathml).toMatchSnapshot();
+    });
+
+    it("should output \\limsup_{x \\rightarrow \\infty} in " +
+            "displaymode correctly", () => {
+        const settings = new Settings({displayMode: true});
+        const mathml = getMathML("\\limsup_{x \\rightarrow \\infty}", settings);
+        expect(mathml).toMatchSnapshot();
+    });
+
     it('should use <mpadded> for raisebox', () => {
         expect(getMathML("\\raisebox{0.25em}{b}")).toMatchSnapshot();
     });

test/screenshotter/ss_data.yaml

@@ -195,8 +195,11 @@ OperatorName: |
         \operatorname{Gam ma}(z) + \operatorname{\Gamma}(z) + \operatorname{}x
     \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}
+    \begin{matrix}
+        {\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} \\
+        \limsup_{x \rightarrow \infty} x \stackrel{?}= \liminf_{x \rightarrow \infty} x
+    \end{matrix}
 OverUnderline: x\underline{x}\underline{\underline{x}}\underline{x_{x_{x_x}}}\underline{x^{x^{x^x}}}\overline{x}\overline{x}\overline{x^{x^{x^x}}} \blue{\overline{\underline{x}}\underline{\overline{x}}}
 OverUnderset: |
     \begin{array}{l}