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To @flow: MacroExpander. (#845)

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* To @flow: MacroExpander.

* Explicitly pass context into defineMacro called with a function.

Instead of binding `this` when `defineMacro` is invoked
with a function, we now pass an explicit context as a
parameter to the function. This is a bit more obvious
and is currently more type-safe due to a bug in `@flow`:
https://github.com/facebook/flow/issues/4809

* Per feedback, rename some types, fields, and variables.
This commit is contained in:
Ashish Myles
2017-09-06 21:39:50 -04:00
committed by Kevin Barabash
parent feef4107df
commit cb7f166a7e
3 changed files with 113 additions and 56 deletions
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51
src/macros.js
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@@ -6,10 +6,39 @@
import symbols from "./symbols";
import utils from "./utils";
import {Token} from "./Token";
// This function might one day accept additional argument and do more things.
function defineMacro(name: string, body: string | () => string) {
module.exports[name] = body;
/**
* Provides context to macros defined by functions. Implemented by
* MacroExpander.
*/
export interface MacroContextInterface {
/**
* Returns the topmost token on the stack, without expanding it.
* Similar in behavior to TeX's `\futurelet`.
*/
future(): Token;
/**
* Expand the next token only once (if possible), and return the resulting
* top token on the stack (without removing anything from the stack).
* Similar in behavior to TeX's `\expandafter\futurelet`.
*/
expandAfterFuture(): Token;
}
/** Macro tokens (in reverse order). */
export type MacroExpansion = {tokens: Token[], numArgs: number};
type MacroDefinition = string | (MacroContextInterface => string) | MacroExpansion;
export type MacroMap = {[string]: MacroDefinition};
const builtinMacros: MacroMap = {};
export default builtinMacros;
// This function might one day accept an additional argument and do more things.
function defineMacro(name: string, body: string | MacroContextInterface => string) {
builtinMacros[name] = body;
}
//////////////////////////////////////////////////////////////////////
@@ -107,14 +136,14 @@ const dotsByToken = {
'\\DOTSX': '\\dotsx',
};
defineMacro("\\dots", function() {
defineMacro("\\dots", function(context) {
// TODO: If used in text mode, should expand to \textellipsis.
// However, in KaTeX, \textellipsis and \ldots behave the same
// (in text mode), and it's unlikely we'd see any of the math commands
// that affect the behavior of \dots when in text mode. So fine for now
// (until we support \ifmmode ... \else ... \fi).
let thedots = '\\dotso';
const next = this.expandAfterFuture().text;
const next = context.expandAfterFuture().text;
if (next in dotsByToken) {
thedots = dotsByToken[next];
} else if (next.substr(0, 4) === '\\not') {
@@ -152,8 +181,8 @@ const spaceAfterDots = {
',': true,
};
defineMacro("\\dotso", function() {
const next = this.future().text;
defineMacro("\\dotso", function(context) {
const next = context.future().text;
if (next in spaceAfterDots) {
return "\\ldots\\,";
} else {
@@ -161,8 +190,8 @@ defineMacro("\\dotso", function() {
}
});
defineMacro("\\dotsc", function() {
const next = this.future().text;
defineMacro("\\dotsc", function(context) {
const next = context.future().text;
// \dotsc uses \extra@ but not \extrap@, instead specially checking for
// ';' and '.', but doesn't check for ','.
if (next in spaceAfterDots && next !== ',') {
@@ -172,8 +201,8 @@ defineMacro("\\dotsc", function() {
}
});
defineMacro("\\cdots", function() {
const next = this.future().text;
defineMacro("\\cdots", function(context) {
const next = context.future().text;
if (next in spaceAfterDots) {
return "\\@cdots\\,";
} else {