Commit node_modules

paige/node_modules/katex/src/utils.js

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+// @flow
+/**
+ * This file contains a list of utility functions which are useful in other
+ * files.
+ */
+
+import type {AnyParseNode} from "./parseNode";
+
+/**
+ * Return whether an element is contained in a list
+ */
+const contains = function<T>(list: Array<T>, elem: T): boolean {
+    return list.indexOf(elem) !== -1;
+};
+
+/**
+ * Provide a default value if a setting is undefined
+ * NOTE: Couldn't use `T` as the output type due to facebook/flow#5022.
+ */
+const deflt = function<T>(setting: T | void, defaultIfUndefined: T): * {
+    return setting === undefined ? defaultIfUndefined : setting;
+};
+
+// hyphenate and escape adapted from Facebook's React under Apache 2 license
+
+const uppercase = /([A-Z])/g;
+const hyphenate = function(str: string): string {
+    return str.replace(uppercase, "-$1").toLowerCase();
+};
+
+const ESCAPE_LOOKUP = {
+    "&": "&amp;",
+    ">": "&gt;",
+    "<": "&lt;",
+    "\"": "&quot;",
+    "'": "&#x27;",
+};
+
+const ESCAPE_REGEX = /[&><"']/g;
+
+/**
+ * Escapes text to prevent scripting attacks.
+ */
+function escape(text: mixed): string {
+    return String(text).replace(ESCAPE_REGEX, match => ESCAPE_LOOKUP[match]);
+}
+
+/**
+ * Sometimes we want to pull out the innermost element of a group. In most
+ * cases, this will just be the group itself, but when ordgroups and colors have
+ * a single element, we want to pull that out.
+ */
+const getBaseElem = function(group: AnyParseNode): AnyParseNode {
+    if (group.type === "ordgroup") {
+        if (group.body.length === 1) {
+            return getBaseElem(group.body[0]);
+        } else {
+            return group;
+        }
+    } else if (group.type === "color") {
+        if (group.body.length === 1) {
+            return getBaseElem(group.body[0]);
+        } else {
+            return group;
+        }
+    } else if (group.type === "font") {
+        return getBaseElem(group.body);
+    } else {
+        return group;
+    }
+};
+
+/**
+ * TeXbook algorithms often reference "character boxes", which are simply groups
+ * with a single character in them. To decide if something is a character box,
+ * we find its innermost group, and see if it is a single character.
+ */
+const isCharacterBox = function(group: AnyParseNode): boolean {
+    const baseElem = getBaseElem(group);
+
+    // These are all they types of groups which hold single characters
+    return baseElem.type === "mathord" ||
+        baseElem.type === "textord" ||
+        baseElem.type === "atom";
+};
+
+export const assert = function<T>(value: ?T): T {
+    if (!value) {
+        throw new Error('Expected non-null, but got ' + String(value));
+    }
+    return value;
+};
+
+/**
+ * Return the protocol of a URL, or "_relative" if the URL does not specify a
+ * protocol (and thus is relative).
+ */
+export const protocolFromUrl = function(url: string): string {
+    const protocol = /^\s*([^\\/#]*?)(?::|&#0*58|&#x0*3a)/i.exec(url);
+    return (protocol != null ? protocol[1] : "_relative");
+};
+
+export default {
+    contains,
+    deflt,
+    escape,
+    hyphenate,
+    getBaseElem,
+    isCharacterBox,
+    protocolFromUrl,
+};