DOMTextScanner (#458)

* Create new class for scanning text in a document

* Update test styles

* Add tests

1 files changed, 181 insertions, 0 deletions

diff --git a/test/test-dom-text-scanner.js b/test/test-dom-text-scanner.js
new file mode 100644
index 00000000..41d6e307
--- /dev/null
+++ b/test/test-dom-text-scanner.js
@@ -0,0 +1,181 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+const fs = require('fs');
+const path = require('path');
+const assert = require('assert');
+const {JSDOM} = require('jsdom');
+const {VM} = require('./yomichan-vm');
+
+
+function createJSDOM(fileName) {
+    const domSource = fs.readFileSync(fileName, {encoding: 'utf8'});
+    return new JSDOM(domSource);
+}
+
+function querySelectorTextNode(element, selector) {
+    let textIndex = -1;
+    const match = /::text$|::nth-text\((\d+)\)$/.exec(selector);
+    if (match !== null) {
+        textIndex = (match[1] ? parseInt(match[1], 10) - 1 : 0);
+        selector = selector.substring(0, selector.length - match[0].length);
+    }
+    const result = element.querySelector(selector);
+    if (textIndex < 0) {
+        return result;
+    }
+    for (let n = result.firstChild; n !== null; n = n.nextSibling) {
+        if (n.nodeType === n.constructor.TEXT_NODE) {
+            if (textIndex === 0) {
+                return n;
+            }
+            --textIndex;
+        }
+    }
+    return null;
+}
+
+
+function getComputedFontSizeInPixels(window, getComputedStyle, element) {
+    for (; element !== null; element = element.parentNode) {
+        if (element.nodeType === window.Node.ELEMENT_NODE) {
+            const fontSize = getComputedStyle(element).fontSize;
+            if (fontSize.endsWith('px')) {
+                const value = parseFloat(fontSize.substring(0, fontSize.length - 2));
+                return value;
+            }
+        }
+    }
+    const defaultFontSize = 14;
+    return defaultFontSize;
+}
+
+function createAbsoluteGetComputedStyle(window) {
+    // Wrapper to convert em units to px units
+    const getComputedStyleOld = window.getComputedStyle.bind(window);
+    return (element, ...args) => {
+        const style = getComputedStyleOld(element, ...args);
+        return new Proxy(style, {
+            get: (target, property) => {
+                let result = target[property];
+                if (typeof result === 'string') {
+                    result = result.replace(/([-+]?\d(?:\.\d)?(?:[eE][-+]?\d+)?)em/g, (g0, g1) => {
+                        const fontSize = getComputedFontSizeInPixels(window, getComputedStyleOld, element);
+                        return `${parseFloat(g1) * fontSize}px`;
+                    });
+                }
+                return result;
+            }
+        });
+    };
+}
+
+
+async function testDomTextScanner(dom, {DOMTextScanner}) {
+    const document = dom.window.document;
+    for (const testElement of document.querySelectorAll('y-test')) {
+        let testData = JSON.parse(testElement.dataset.testData);
+        if (!Array.isArray(testData)) {
+            testData = [testData];
+        }
+        for (const testDataItem of testData) {
+            let {
+                node,
+                offset,
+                length,
+                forcePreserveWhitespace,
+                generateLayoutContent,
+                reversible,
+                expected: {
+                    node: expectedNode,
+                    offset: expectedOffset,
+                    content: expectedContent
+                }
+            } = testDataItem;
+
+            node = querySelectorTextNode(testElement, node);
+            expectedNode = querySelectorTextNode(testElement, expectedNode);
+
+            // Standard test
+            {
+                const scanner = new DOMTextScanner(node, offset, forcePreserveWhitespace, generateLayoutContent);
+                scanner.seek(length);
+
+                const {node: actualNode1, offset: actualOffset1, content: actualContent1} = scanner;
+                assert.strictEqual(actualContent1, expectedContent);
+                assert.strictEqual(actualOffset1, expectedOffset);
+                assert.strictEqual(actualNode1, expectedNode);
+            }
+
+            // Substring tests
+            for (let i = 1; i <= length; ++i) {
+                const scanner = new DOMTextScanner(node, offset, forcePreserveWhitespace, generateLayoutContent);
+                scanner.seek(length - i);
+
+                const {content: actualContent} = scanner;
+                assert.strictEqual(actualContent, expectedContent.substring(0, expectedContent.length - i));
+            }
+
+            if (reversible === false) { continue; }
+
+            // Reversed test
+            {
+                const scanner = new DOMTextScanner(expectedNode, expectedOffset, forcePreserveWhitespace, generateLayoutContent);
+                scanner.seek(-length);
+
+                const {content: actualContent} = scanner;
+                assert.strictEqual(actualContent, expectedContent);
+            }
+
+            // Reversed substring tests
+            for (let i = 1; i <= length; ++i) {
+                const scanner = new DOMTextScanner(expectedNode, expectedOffset, forcePreserveWhitespace, generateLayoutContent);
+                scanner.seek(-(length - i));
+
+                const {content: actualContent} = scanner;
+                assert.strictEqual(actualContent, expectedContent.substring(i));
+            }
+        }
+    }
+}
+
+
+async function testDocument1() {
+    const dom = createJSDOM(path.join(__dirname, 'data', 'html', 'test-dom-text-scanner.html'));
+    const window = dom.window;
+    try {
+        const {document, Node, Range} = window;
+
+        window.getComputedStyle = createAbsoluteGetComputedStyle(window);
+
+        const vm = new VM({document, window, Range, Node});
+        vm.execute('fg/js/dom-text-scanner.js');
+        const DOMTextScanner = vm.get('DOMTextScanner');
+
+        await testDomTextScanner(dom, {DOMTextScanner});
+    } finally {
+        window.close();
+    }
+}
+
+
+async function main() {
+    await testDocument1();
+}
+
+
+if (require.main === module) { main(); }