scribble-math/Lexer.js
Emily Eisenberg d729ba5281 Add a \color command for custom colors
Summary:
Keep track of the color inside the style now, and use that when we are
rendering things. Added a custom lexing mode to handle lexing colors correctly.
Prefixed the old katex colors (internally) with "katex-" to distinguish them
from CSS colors.

Test Plan:
 - Run the normal tests, see they work
 - Run the huxley tests, see that they didn't change except for the color one
   which looks right

Reviewers: alpert

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D7763
2014-03-27 12:34:45 -04:00

117 lines
3.2 KiB
JavaScript

var ParseError = require("./ParseError");
// The main lexer class
function Lexer(input) {
this._input = input;
};
// The result of a single lex
function LexResult(type, text, position) {
this.type = type;
this.text = text;
this.position = position;
}
// "normal" types of tokens
var mathNormals = [
[/^[/|@."`0-9]/, "textord"],
[/^[a-zA-Z]/, "mathord"],
[/^[*+-]/, "bin"],
[/^[=<>:]/, "rel"],
[/^[,;]/, "punct"],
[/^'/, "'"],
[/^\^/, "^"],
[/^_/, "_"],
[/^{/, "{"],
[/^}/, "}"],
[/^[(\[]/, "open"],
[/^[)\]?!]/, "close"]
];
var textNormals = [
[/^[a-zA-Z0-9`!@*()-=+\[\]'";:?\/.,]/, "textord"],
[/^{/, "{"],
[/^}/, "}"]
];
// Build a regex to easily parse the functions
var anyFunc = /^\\(?:[a-zA-Z]+|.)/;
Lexer.prototype._innerLex = function(pos, normals, ignoreWhitespace) {
var input = this._input.slice(pos);
// Get rid of whitespace
if (ignoreWhitespace) {
var whitespace = input.match(/^\s*/)[0];
pos += whitespace.length;
input = input.slice(whitespace.length);
} else {
// Do the funky concatenation of whitespace
var whitespace = input.match(/^( +|\\ +)/);
if (whitespace !== null) {
return new LexResult(" ", " ", pos + whitespace[0].length);
}
}
// If there's no more input to parse, return an EOF token
if (input.length === 0) {
return new LexResult("EOF", null, pos);
}
var match;
if ((match = input.match(anyFunc))) {
// If we match one of the tokens, extract the type
return new LexResult(match[0], match[0], pos + match[0].length);
} else {
// Otherwise, we look through the normal token regexes and see if it's
// one of them.
for (var i = 0; i < normals.length; i++) {
var normal = normals[i];
if ((match = input.match(normal[0]))) {
// If it is, return it
return new LexResult(
normal[1], match[0], pos + match[0].length);
}
}
}
// We didn't match any of the tokens, so throw an error.
throw new ParseError("Unexpected character: '" + input[0] +
"' at position " + pos);
}
// A regex to match a CSS color (like #ffffff or BlueViolet)
var cssColor = /^(#[a-z0-9]+|[a-z]+)/i;
Lexer.prototype._innerLexColor = function(pos) {
var input = this._input.slice(pos);
// Ignore whitespace
var whitespace = input.match(/^\s*/)[0];
pos += whitespace.length;
input = input.slice(whitespace.length);
var match;
if ((match = input.match(cssColor))) {
// If we look like a color, return a color
return new LexResult("color", match[0], pos + match[0].length);
}
// We didn't match a color, so throw an error.
throw new ParseError("Invalid color at position " + pos);
};
// Lex a single token
Lexer.prototype.lex = function(pos, mode) {
if (mode === "math") {
return this._innerLex(pos, mathNormals, true);
} else if (mode === "text") {
return this._innerLex(pos, textNormals, false);
} else if (mode === "color") {
return this._innerLexColor(pos);
}
};
module.exports = Lexer;