Add stringify function (convert js object to java properties string)

Author: nathan818fr

src/java-props.ts

@@ -1,4 +1,4 @@
-import {convertLine, LineReader} from './utils';
+import {decodeLine, encodeLine, LineReader} from './utils';
 
 export interface Properties {
     [key: string]: string;
@@ -45,13 +45,24 @@ export function parse(str: string): Properties {
             valueStart++;
         }
 
-        const key = convertLine(line.substring(0, keyLen));
-        const value = convertLine(line.substring(valueStart));
+        const key = decodeLine(line.substring(0, keyLen));
+        const value = decodeLine(line.substring(valueStart));
         result[key] = value;
     }
     return result;
 }
 
+export function stringify(props: Properties): string { // TODO: Add unit-tests
+    let str = '';
+    for (const key in props) {
+        if (Object.prototype.hasOwnProperty.call(props, key)) {
+            const value = props[key];
+            str += encodeLine(key, true) + ': ' + encodeLine(value) + '\n';
+        }
+    }
+    return str;
+}
+
 export default {
     parse,
 };

src/utils.ts

@@ -1,10 +1,13 @@
-const CONVERT_RXP = /(?:\\u(.{0,4})|\\(.?))/g;
-const UNICODE_RXP = /^[0-9a-fA-F]{4}$/;
+const DECODE_PATTERN = /(?:\\u(.{0,4})|\\(.?))/g;
+const UNICODE_PATTERN = /^[0-9a-fA-F]{4}$/;
 
-export function convertLine(line: string): string {
-    return line.replace(CONVERT_RXP, (_, unicode, char) => {
+const ENCODE_PATTERN = /(?:[\u0000-\u001F\\\u007F-\uFFFF])/g;
+const ENCODE_KEY_PATTERN = /(?:[\u0000-\u0020!#:=\\\u007F-\uFFFF])/g; // ENCODE_PATTERN with separators + comments
+
+export function decodeLine(line: string): string {
+    return line.replace(DECODE_PATTERN, (_, unicode, char) => {
         if (unicode !== undefined) {
-            if (!unicode.match(UNICODE_RXP)) {
+            if (!unicode.match(UNICODE_PATTERN)) {
                 throw new Error('Malformed \\uxxxx encoding.');
             }
             const charVal = parseInt(unicode, 16);
@@ -23,6 +26,40 @@ export function convertLine(line: string): string {
     });
 }
 
+export function encodeLine(line: string, isKey?: boolean): string {
+    line = line.replace(isKey ? ENCODE_KEY_PATTERN : ENCODE_PATTERN, (c) => {
+        if (c === '\t') {
+            return '\\t';
+        } else if (c === '\r') {
+            return '\\r';
+        } else if (c === '\n') {
+            return '\\n';
+        } else if (c === '\f') {
+            return '\\f';
+        } else if (c >= ' ' && c <= '~') {
+            return '\\' + c;
+        } else {
+            const code = c.charCodeAt(0);
+            if (code < 16) return '\\u000' + code.toString(16).toUpperCase();
+            if (code < 256) return '\\u00' + code.toString(16).toUpperCase();
+            if (code < 4096) return '\\u0' + code.toString(16).toUpperCase();
+            return '\\u' + code.toString(16).toUpperCase();
+        }
+    });
+    if (!isKey) {
+        const c = line.charAt(0);
+        if (c === ' ' || c === '\t' || c === '\f') {
+            line = '\\' + line;
+        }
+    }
+    return line;
+}
+
+/**
+ * @deprecated Use {@link #decodeLine}.
+ */
+export const convertLine = decodeLine;
+
 export class LineReader {
     private readonly str: string;
     private readonly strLen: number;