clipper: implement web clipper core library

packages/clipper/src/css-tokenizer.ts

@@ -0,0 +1,176 @@
+/*
+This file is part of the Notesnook project (https://notesnook.com/)
+
+Copyright (C) 2022 Streetwriters (Private) Limited
+
+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 <http://www.gnu.org/licenses/>.
+*/
+
+const from = String.fromCharCode;
+
+function trim(value: string): string {
+  return value.trim();
+}
+
+function charat(value: string, index: number): number {
+  return value.charCodeAt(index) | 0;
+}
+
+function strlen(value: string): number {
+  return value.length;
+}
+
+function substr(value: string, begin: number, end: number): string {
+  return value.slice(begin, end);
+}
+
+function append<T>(value: T, array: T[]): T {
+  array.push(value);
+  return value;
+}
+
+let line = 1;
+let column = 1;
+let length = 0;
+let position = 0;
+let character = 0;
+let characters = "";
+
+function next(): number {
+  character = position < length ? charat(characters, position++) : 0;
+
+  if ((column++, character === 10)) (column = 1), line++;
+
+  return character;
+}
+
+function peek(): number {
+  return charat(characters, position);
+}
+
+function slice(begin: number, end: number): string {
+  return substr(characters, begin, end);
+}
+
+function token(type: number): number {
+  switch (type) {
+    // \0 \t \n \r \s whitespace token
+    case 0:
+    case 9:
+    case 10:
+    case 13:
+    case 32:
+      return 5;
+
+    // ! + , / > @ ~ isolate token
+    case 33:
+    case 42:
+    case 43:
+    case 44:
+    case 47:
+    case 62:
+    case 64:
+    case 126:
+    case 59: /* ; { } breakpoint token */
+    case 123:
+    case 125:
+      return 4;
+    // : accompanied token
+    case 58:
+      return 3;
+    // " ' ( [ opening delimit token
+    case 34:
+    case 39:
+    case 40:
+    case 91:
+      return 2;
+    // ) ] closing delimit token
+    case 41:
+    case 93:
+      return 1;
+  }
+
+  return 0;
+}
+
+function alloc(value: string): [] {
+  line = column = 1;
+  length = strlen((characters = value));
+  position = 0;
+  return [];
+}
+
+function dealloc<T>(value: T): T {
+  characters = "";
+  return value;
+}
+
+function delimit(type: number): string {
+  return trim(
+    slice(
+      position - 1,
+      delimiter(type === 91 ? type + 2 : type === 40 ? type + 1 : type)
+    )
+  );
+}
+
+export function tokenize(value: string): string[] {
+  return dealloc(tokenizer(alloc(value)));
+}
+
+function tokenizer(children: string[]): string[] {
+  while (next())
+    switch (token(character)) {
+      case 0:
+        append(identifier(position - 1), children);
+        break;
+      case 2:
+        append(delimit(character), children);
+        break;
+      default:
+        append(from(character), children);
+    }
+
+  return children;
+}
+
+function delimiter(type: number): number {
+  while (next())
+    switch (character) {
+      // ] ) " '
+      case type:
+        return position;
+      // " '
+      case 34:
+      case 39:
+        if (type !== 34 && type !== 39) delimiter(character);
+        break;
+      // (
+      case 40:
+        if (type === 41) delimiter(type);
+        break;
+      // \
+      case 92:
+        next();
+        break;
+    }
+
+  return position;
+}
+
+function identifier(index: number): string {
+  while (!token(peek())) next();
+
+  return slice(index, position);
+}