feat(function): add allowedInArgument instead of greediness property (#2134)

* Remove `greediness` property Use boolean `grouped` property instead, which is more consistent with LaTeX. BREAKING CHANGE: \cfrac, \color, \textcolor, \colorbox, \fcolorbox are no longer grouped. * Rename grouped to allowedInArgument * Reenable tests * Update documentation * Fix typo Co-authored-by: Kevin Barabash <kevinb@khanacademy.org>
2025-10-07 20:28:38 +00:00 · 2020-09-07 13:38:17 +09:00
parent 37990cc5b3
commit 5a90558116
10 changed files with 53 additions and 61 deletions
--- a/docs/migration.md
+++ b/docs/migration.md
@@ -9,8 +9,8 @@ some gaps between KaTeX and LaTeX and therefore there may be breaking changes.
 ## Macro arguments
 Tokens will not be expanded while parsing a macro argument. For example, `\frac\foo\foo`,
 where the `\foo` is defined as `12`, will be parsed as `\frac{12}{12}`, not
-`\frac{1}{2}12`. <!--To expand the argument before parsing, `\expandafter` can
-be used` like `\expandafter\frac\foo\foo`.-->
+`\frac{1}{2}12`. To expand the argument before parsing, `\expandafter` can
+be used like `\expandafter\frac\foo\foo`.

 ## `\def`
 `\def` no longer accepts a control sequence enclosed in braces. For example,
@@ -22,3 +22,9 @@ It also no longer accepts replacement text not enclosed in braces. For example,
 ## `\newline` and `\cr`
 `\newline` and `\cr` no longer takes an optional size argument. To specify vertical
 spacing, `\\` should be used.
+
+## `\cfrac`, `\color`, `\textcolor`, `\colorbox`, `\fcolorbox`
+They are no longer allowed as an argument to primitive commands, such as `\sqrt`
+(without the optional argument) and super/subscript. For example,
+`\sqrt\textcolor{red}{x}` no longer works and should be changed to
+`\sqrt{\textcolor{red}{x}}`.
--- a/src/Parser.js
+++ b/src/Parser.js
@@ -247,9 +247,6 @@ export default class Parser {
        }
    }

-    // The greediness of a superscript or subscript
-    static SUPSUB_GREEDINESS = 1;
-
    /**
     * Handle a subscript or superscript with nice errors.
     */
@@ -260,7 +257,7 @@ export default class Parser {
        const symbol = symbolToken.text;
        this.consume();
        this.consumeSpaces(); // ignore spaces before sup/subscript argument
-        const group = this.parseGroup(name, Parser.SUPSUB_GREEDINESS);
+        const group = this.parseGroup(name);

        if (!group) {
            throw new ParseError(
@@ -305,7 +302,7 @@ export default class Parser {
    parseAtom(breakOnTokenText?: BreakToken): ?AnyParseNode {
        // The body of an atom is an implicit group, so that things like
        // \left(x\right)^2 work correctly.
-        const base = this.parseGroup("atom", null, breakOnTokenText);
+        const base = this.parseGroup("atom", breakOnTokenText);

        // In text mode, we don't have superscripts or subscripts
        if (this.mode === "text") {
@@ -402,8 +399,7 @@ export default class Parser {
     */
    parseFunction(
        breakOnTokenText?: BreakToken,
-        name?: string, // For error reporting.
-        greediness?: ?number,
+        name?: string, // For determining its context
    ): ?AnyParseNode {
        const token = this.fetch();
        const func = token.text;
@@ -413,7 +409,7 @@ export default class Parser {
        }
        this.consume(); // consume command token

-        if (greediness != null && funcData.greediness <= greediness) {
+        if (name && name !== "atom" && !funcData.allowedInArgument) {
            throw new ParseError(
                "Got function '" + func + "' with no arguments" +
                (name ? " as " + name : ""), token);
@@ -468,7 +464,6 @@ export default class Parser {
            return {args: [], optArgs: []};
        }

-        const baseGreediness = funcData.greediness;
        const args = [];
        const optArgs = [];

@@ -483,7 +478,7 @@ export default class Parser {
            }

            const arg = this.parseGroupOfType(`argument to '${func}'`,
-                argType, isOptional, baseGreediness);
+                argType, isOptional);
            if (isOptional) {
                optArgs.push(arg);
            } else if (arg != null) {
@@ -503,7 +498,6 @@ export default class Parser {
        name: string,
        type: ?ArgType,
        optional: boolean,
-        greediness: ?number,
    ): ?AnyParseNode {
        switch (type) {
            case "color":
@@ -538,7 +532,7 @@ export default class Parser {
                if (optional) {
                    throw new ParseError("A primitive argument cannot be optional");
                }
-                const group = this.parseGroup(name, greediness);
+                const group = this.parseGroup(name);
                if (group == null) {
                    throw new ParseError("Expected group as " + name, this.fetch());
                }
@@ -744,7 +738,6 @@ export default class Parser {
     */
    parseGroup(
        name: string, // For error reporting.
-        greediness?: ?number,
        breakOnTokenText?: BreakToken,
    ): ?AnyParseNode {
        const firstToken = this.fetch();
@@ -776,7 +769,7 @@ export default class Parser {
        } else {
            // If there exists a function with this name, parse the function.
            // Otherwise, just return a nucleus
-            result = this.parseFunction(breakOnTokenText, name, greediness) ||
+            result = this.parseFunction(breakOnTokenText, name) ||
                this.parseSymbol();
            if (result == null && text[0] === "\\" &&
                    !implicitCommands.hasOwnProperty(text)) {
--- a/src/defineEnvironment.js
+++ b/src/defineEnvironment.js
@@ -52,7 +52,6 @@ export type EnvSpec<NODETYPE: NodeType> = {|
    type: NODETYPE, // Need to use the type to avoid error. See NOTES below.
    numArgs: number,
    argTypes?: ArgType[],
-    greediness: number,
    allowedInText: boolean,
    numOptionalArgs: number,
    handler: EnvHandler,
@@ -99,7 +98,6 @@ export default function defineEnvironment<NODETYPE: NodeType>({
    const data = {
        type,
        numArgs: props.numArgs || 0,
-        greediness: 1,
        allowedInText: false,
        numOptionalArgs: 0,
        handler,
--- a/src/defineFunction.js
+++ b/src/defineFunction.js
@@ -46,26 +46,10 @@ export type FunctionPropSpec = {
    // should appear before types for mandatory arguments.
    argTypes?: ArgType[],

-    // The greediness of the function to use ungrouped arguments.
-    //
-    // E.g. if you have an expression
-    //   \sqrt \frac 1 2
-    // since \frac has greediness=2 vs \sqrt's greediness=1, \frac
-    // will use the two arguments '1' and '2' as its two arguments,
-    // then that whole function will be used as the argument to
-    // \sqrt. On the other hand, the expressions
-    //   \frac \frac 1 2 3
-    // and
-    //   \frac \sqrt 1 2
-    // will fail because \frac and \frac have equal greediness
-    // and \sqrt has a lower greediness than \frac respectively. To
-    // make these parse, we would have to change them to:
-    //   \frac {\frac 1 2} 3
-    // and
-    //   \frac {\sqrt 1} 2
-    //
-    // The default value is `1`
-    greediness?: number,
+    // Whether it expands to a single token or a braced group of tokens.
+    // If it's grouped, it can be used as an argument to primitive commands,
+    // such as \sqrt (without the optional argument) and super/subscript.
+    allowedInArgument?: boolean,

    // Whether or not the function is allowed inside text mode
    // (default false)
@@ -126,7 +110,7 @@ export type FunctionSpec<NODETYPE: NodeType> = {|
    type: NODETYPE, // Need to use the type to avoid error. See NOTES below.
    numArgs: number,
    argTypes?: ArgType[],
-    greediness: number,
+    allowedInArgument: boolean,
    allowedInText: boolean,
    allowedInMath: boolean,
    numOptionalArgs: number,
@@ -183,7 +167,7 @@ export default function defineFunction<NODETYPE: NodeType>({
        type,
        numArgs: props.numArgs,
        argTypes: props.argTypes,
-        greediness: (props.greediness === undefined) ? 1 : props.greediness,
+        allowedInArgument: !!props.allowedInArgument,
        allowedInText: !!props.allowedInText,
        allowedInMath: (props.allowedInMath === undefined)
            ? true
--- a/src/functions/color.js
+++ b/src/functions/color.js
@@ -38,7 +38,6 @@ defineFunction({
    props: {
        numArgs: 2,
        allowedInText: true,
-        greediness: 3,
        argTypes: ["color", "original"],
    },
    handler({parser}, args) {
@@ -61,7 +60,6 @@ defineFunction({
    props: {
        numArgs: 1,
        allowedInText: true,
-        greediness: 3,
        argTypes: ["color"],
    },
    handler({parser, breakOnTokenText}, args) {
--- a/src/functions/enclose.js
+++ b/src/functions/enclose.js
@@ -225,7 +225,6 @@ defineFunction({
    props: {
        numArgs: 2,
        allowedInText: true,
-        greediness: 3,
        argTypes: ["color", "text"],
    },
    handler({parser, funcName}, args, optArgs) {
@@ -249,7 +248,6 @@ defineFunction({
    props: {
        numArgs: 3,
        allowedInText: true,
-        greediness: 3,
        argTypes: ["color", "color", "text"],
    },
    handler({parser, funcName}, args, optArgs) {
--- a/src/functions/font.js
+++ b/src/functions/font.js
@@ -44,7 +44,7 @@ defineFunction({
    ],
    props: {
        numArgs: 1,
-        greediness: 2,
+        allowedInArgument: true,
    },
    handler: ({parser, funcName}, args) => {
        const body = normalizeArgument(args[0]);
@@ -68,7 +68,6 @@ defineFunction({
    names: ["\\boldsymbol", "\\bm"],
    props: {
        numArgs: 1,
-        greediness: 2,
    },
    handler: ({parser}, args) => {
        const body = args[0];
--- a/src/functions/genfrac.js
+++ b/src/functions/genfrac.js
@@ -241,14 +241,14 @@ const mathmlBuilder = (group, options) => {
 defineFunction({
    type: "genfrac",
    names: [
-        "\\cfrac", "\\dfrac", "\\frac", "\\tfrac",
+        "\\dfrac", "\\frac", "\\tfrac",
        "\\dbinom", "\\binom", "\\tbinom",
        "\\\\atopfrac", // can’t be entered directly
        "\\\\bracefrac", "\\\\brackfrac",   // ditto
    ],
    props: {
        numArgs: 2,
-        greediness: 2,
+        allowedInArgument: true,
    },
    handler: ({parser, funcName}, args) => {
        const numer = args[0];
@@ -259,7 +259,6 @@ defineFunction({
        let size = "auto";

        switch (funcName) {
-            case "\\cfrac":
            case "\\dfrac":
            case "\\frac":
            case "\\tfrac":
@@ -290,7 +289,6 @@ defineFunction({
        }

        switch (funcName) {
-            case "\\cfrac":
            case "\\dfrac":
            case "\\dbinom":
                size = "display";
@@ -304,7 +302,7 @@ defineFunction({
        return {
            type: "genfrac",
            mode: parser.mode,
-            continued: funcName === "\\cfrac",
+            continued: false,
            numer,
            denom,
            hasBarLine,
@@ -319,6 +317,31 @@ defineFunction({
    mathmlBuilder,
 });

+defineFunction({
+    type: "genfrac",
+    names: ["\\cfrac"],
+    props: {
+        numArgs: 2,
+    },
+    handler: ({parser, funcName}, args) => {
+        const numer = args[0];
+        const denom = args[1];
+
+        return {
+            type: "genfrac",
+            mode: parser.mode,
+            continued: true,
+            numer,
+            denom,
+            hasBarLine: true,
+            leftDelim: null,
+            rightDelim: null,
+            size: "display",
+            barSize: null,
+        };
+    },
+});
+
 // Infix generalized fractions -- these are not rendered directly, but replaced
 // immediately by one of the variants above.
 defineFunction({
@@ -374,7 +397,7 @@ defineFunction({
    names: ["\\genfrac"],
    props: {
        numArgs: 6,
-        greediness: 6,
+        allowedInArgument: true,
        argTypes: ["math", "math", "size", "text", "math", "math"],
    },
    handler({parser}, args) {
--- a/src/functions/text.js
+++ b/src/functions/text.js
@@ -48,7 +48,7 @@ defineFunction({
    props: {
        numArgs: 1,
        argTypes: ["text"],
-        greediness: 2,
+        allowedInArgument: true,
        allowedInText: true,
    },
    handler({parser, funcName}, args) {
--- a/test/katex-spec.js
+++ b/test/katex-spec.js
@@ -849,13 +849,6 @@ describe("A color parser", function() {
        expect(newColorExpression).toParse();
    });

-    it("should have correct greediness", function() {
-        expect`\textcolor{red}a`.toParse();
-        expect`\textcolor{red}{\text{a}}`.toParse();
-        expect`\textcolor{red}\text{a}`.not.toParse();
-        expect`\textcolor{red}\frac12`.not.toParse();
-    });
-
    it("should use one-argument \\color by default", function() {
        expect(oldColorExpression).toParseLike`\textcolor{#fA6}{xy}`;
    });
@@ -1619,7 +1612,7 @@ describe("A font parser", function() {
        expect(bf.body.body[2].text).toEqual("c");
    });

-    it("should have the correct greediness", function() {
+    it("should be allowed in the argument", function() {
        expect`e^\mathbf{x}`.toParse();
    });