From 7ec455083feef02deebb0e64d0e5414213ed4196 Mon Sep 17 00:00:00 2001 From: Martin von Gagern Date: Fri, 6 Jan 2017 18:52:50 +0100 Subject: [PATCH] Builtin macros, macro arguments, overset and underset * Ship predefined macros with the library, in macros.js. * Allow macro arguments #1 and so on, with argument count deduced from string. * Use these features to implement \overset and \underset, fixes #484. --- .eslintrc | 2 +- package.json | 1 + src/MacroExpander.js | 76 ++++++++++++++++++++++++++++++++++++++++++-- src/macros.js | 15 +++++++++ test/katex-spec.js | 7 ++++ 5 files changed, 98 insertions(+), 3 deletions(-) create mode 100644 src/macros.js diff --git a/.eslintrc b/.eslintrc index 96821cc..74c9e4d 100644 --- a/.eslintrc +++ b/.eslintrc @@ -39,7 +39,7 @@ "no-with": 2, "one-var": [2, "never"], "prefer-const": 2, - "prefer-spread": 2, + "prefer-spread": 0, // re-enable once we use es6 "semi": [2, "always"], "space-before-blocks": 2, "space-before-function-paren": [2, "never"], diff --git a/package.json b/package.json index 4f00ff3..6e794ff 100644 --- a/package.json +++ b/package.json @@ -30,6 +30,7 @@ "less": "~2.7.1", "morgan": "^1.7.0", "nomnom": "^1.8.1", + "object-assign": "^4.1.0", "pako": "1.0.4", "selenium-webdriver": "^2.48.2", "sri-toolbox": "^0.2.0", diff --git a/src/MacroExpander.js b/src/MacroExpander.js index 8569e6a..7ea8d31 100644 --- a/src/MacroExpander.js +++ b/src/MacroExpander.js @@ -4,10 +4,13 @@ */ const Lexer = require("./Lexer"); +const builtinMacros = require("./macros"); +const ParseError = require("./ParseError"); +const objectAssign = require("object-assign"); function MacroExpander(input, macros) { this.lexer = new Lexer(input); - this.macros = macros; + this.macros = objectAssign({}, builtinMacros, macros); this.stack = []; // contains tokens in REVERSE order this.discardedWhiteSpace = []; } @@ -25,18 +28,87 @@ MacroExpander.prototype.nextToken = function() { if (!(name.charAt(0) === "\\" && this.macros.hasOwnProperty(name))) { return topToken; } + let tok; let expansion = this.macros[name]; if (typeof expansion === "string") { + let numArgs = 0; + if (expansion.indexOf("#") !== -1) { + const stripped = expansion.replace(/##/g, ""); + while (stripped.indexOf("#" + (numArgs + 1)) !== -1) { + ++numArgs; + } + } const bodyLexer = new Lexer(expansion); expansion = []; - let tok = bodyLexer.lex(); + tok = bodyLexer.lex(); while (tok.text !== "EOF") { expansion.push(tok); tok = bodyLexer.lex(); } expansion.reverse(); // to fit in with stack using push and pop + expansion.numArgs = numArgs; this.macros[name] = expansion; } + if (expansion.numArgs) { + const args = []; + let i; + // obtain arguments, either single token or balanced {…} group + for (i = 0; i < expansion.numArgs; ++i) { + const startOfArg = this.get(true); + if (startOfArg.text === "{") { + const arg = []; + let depth = 1; + while (depth !== 0) { + tok = this.get(false); + arg.push(tok); + if (tok.text === "{") { + ++depth; + } else if (tok.text === "}") { + --depth; + } else if (tok.text === "EOF") { + throw new ParseError( + "End of input in macro argument", + startOfArg); + } + } + arg.pop(); // remove last } + arg.reverse(); // like above, to fit in with stack order + args[i] = arg; + } else if (startOfArg.text === "EOF") { + throw new ParseError( + "End of input expecting macro argument", topToken); + } else { + args[i] = [startOfArg]; + } + } + // paste arguments in place of the placeholders + expansion = expansion.slice(); // make a shallow copy + for (i = expansion.length - 1; i >= 0; --i) { + tok = expansion[i]; + if (tok.text === "#") { + if (i === 0) { + throw new ParseError( + "Incomplete placeholder at end of macro body", + tok); + } + tok = expansion[--i]; // next token on stack + if (tok.text === "#") { // ## → # + expansion.splice(i + 1, 1); // drop first # + } else if (/^[1-9]$/.test(tok.text)) { + // expansion.splice(i, 2, arg[0], arg[1], …) + // to replace placeholder with the indicated argument. + // TODO: use spread once we move to ES2015 + expansion.splice.apply( + expansion, + [i, 2].concat(args[tok.text - 1])); + } else { + throw new ParseError( + "Not a valid argument number", + tok); + } + } + } + } this.stack = this.stack.concat(expansion); } }; diff --git a/src/macros.js b/src/macros.js new file mode 100644 index 0000000..197145c --- /dev/null +++ b/src/macros.js @@ -0,0 +1,15 @@ +/** + * Predefined macros for KaTeX. + * This can be used to define some commands in terms of others. + */ + +module.exports = { + + ////////////////////////////////////////////////////////////////////// + // amsmath.sty + + // \def\overset#1#2{\binrel@{#2}\binrel@@{\mathop{\kern\z@#2}\limits^{#1}}} + "\\overset": "\\mathop{#2}\\limits^{#1}", + "\\underset": "\\mathop{#2}\\limits_{#1}", + +}; diff --git a/test/katex-spec.js b/test/katex-spec.js index 36dd5f5..651df70 100644 --- a/test/katex-spec.js +++ b/test/katex-spec.js @@ -2011,6 +2011,13 @@ describe("A macro expander", function() { "\\bar": "a", }); }); + + it("should expand the \overset macro as expected", function() { + expect("\\overset?=").toParseLike("\\mathop{=}\\limits^{?}"); + expect("\\overset{x=y}{\sqrt{ab}}") + .toParseLike("\\mathop{\sqrt{ab}}\\limits^{x=y}"); + expect("\\overset {?} =").toParseLike("\\mathop{=}\\limits^{?}"); + }); }); describe("A parser taking String objects", function() {