String

Overview

String objects are a quoted string like "aaa". You can write it as a double-quoted or single-quoted string.

Basic Methods

There is a special object named as String. The methods of String can be used for string values directly.

Method	Meaning
String.startsWith(val, str)	true if val is started with str.
String.endsWith(val, str)	true if val is ended with str.
String.find(val, str)	The position started from 0 is returned if str is found in str. -1 will be returned when it is not found.
String.subString(val, start[, len])	A sub string in val will be returned.
String.replace(val, cond, repl)	All of matched sub string with cond in val will be replaced by repl. cond should be a string or a Regex object.
String.toInt(val)	Converts val into Integer.
String.toDouble(val)	Converts val into Double.
String.parentPath(val)	By recognizing val as a path string, it will return the parent part. ex) "ab/cd/ef.x".parentPath() will return "ab/cd".
String.filename(val)	By recognizing val as a path string, it will return the filename part. ex) "ab/cd/ef.x".filename() will return "ef.x"
String.stem(val)	By recognizing val as a path string, it will return the stem part. ex) "ab/cd/ef.x".stem() will return "ef"
String.extension(val)	By recognizing val as a path string, it will return the extension part. ex) "ab/cd/ef.x".extension() will return ".x"
String.split(val, sep)	It will return an array splitted val by sep. sep should be a string or a Regex object.
String.each(val, callback)	It will call callback for each character. The second argument for callback function will be available as an index started from 0.

The String object can hold any methods you want to add. For example, see below.

String.greeting = function(name) {
    System.println("Hello, I am %{name}.");
};

"John".greeting();

Let’s run it.

Hello, I am John.

The receiver comes in the first argument.

Escape Sequence

You can use an escape sequence easily via some String methods. Those methods currently are supporting to decorate a string such as a coloring.

Example of String Decoration

Here is an example of decorating a string. The decoration range is only a specified string, and the decoration will be automatically cleared.

var s = "This is a pen";
System.println(s.red(.white));                              // => \e31;47[mThis is a pen\e[0m
System.println(s.yellow());                                 // => \e33[mThis is a pen\e[0m
System.println(s.bold().yellow());                          // => \e33;1[mThis is a pen\e[0m
System.println("xyz:" + s.yellow(.red).underline().bold()); // => xyz:\e33;41;4;1[mThis is a pen\e[0m
System.println(s.black(.white).underline());                // => \e30;47;4[mThis is a pen\e[0m
System.println(s.red().bold().underline() + ":aaa");        // => \e31;1;4[mThis is a pen\e[0m:aaa

Here is an actual result.

Methods

Here are methods of coloring and decorating.

Method	Meaning
black(bgColor)	Makes a foreground color black, and optionally possible to set a background color.
red(bgColor)	Makes a foreground color red, and optionally possible to set a background color.
green(bgColor)	Makes a foreground color green, and optionally possible to set a background color.
yellow(bgColor)	Makes a foreground color yellow, and optionally possible to set a background color.
blue(bgColor)	Makes a foreground color blue, and optionally possible to set a background color.
magenta(bgColor)	Makes a foreground color magenta, and optionally possible to set a background color.
cyan(bgColor)	Makes a foreground color cyan, and optionally possible to set a background color.
white(bgColor)	Makes a foreground color white, and optionally possible to set a background color.
bold()	Makes a string bold.
underline()	Adds underline to a string.

bgColor is optional and it is . style such as .white. Here is a possible background color setting. If nothing specified, there is no change to a background color.

bgColor	Meaning
.black	Makes a background color black.
.red	Makes a background color red.
.green	Makes a background color green.
.yellow	Makes a background color yellow.
.blue	Makes a background color blue.
.magenta	Makes a background color magenta.
.cyan	Makes a background color cyan.
.white	Makes a background color white.

Special operator

/ operator

You can use the operator of / to join strings by /. It is useful for the path operation.

var a = "aa/bb" / "ccdd";   // => "aa/bb/ccdd"
var b = "aa/bb/" / "ccdd";  // => "aa/bb/ccdd"
var c = "aa/bb" / "/ccdd";  // => "aa/bb/ccdd"

=~ operator

If you use the operator of =~ for a string, the right hand side should be a Regex object. Otherwise an exception will be raised.

!~ operator

If you use the operator of !~ for a string, the right hand side should be a Regex object. Otherwise an exception will be raised.

Postfix [] operator

You can use [] operator to access a character in a string by index. The value will be an integer number as a character code. Therefore if you want to check the 5th character is 'a', you should write it as follows.

if (str[5] == 'a'[0]) {
    /* ... */
}

Note that it is different from C code. You need [0] because 'a' is not a character code but *a string literal**.

Unary * operator

Unary * operator for a string will convert it to an array of character codes.

var a = *"abc";  // => [97, 98, 99]

By the way, unary * operator for an array will convert it back to a string.

Examples

Example 1. Normal case

Code

System.println("This is a pen.");

Result

This is a pen.

Example 2. Greeting

Code

String.greeting = function(name) {
    System.println("Hello, I am %{name}.");
};

"John".greeting();

Result

Hello, I am John.

Example 3. Path operator

Code

var a = "aa/bb" / "ccdd";   // => "aa/bb/ccdd"
var b = "aa/bb/" / "ccdd";  // => "aa/bb/ccdd"
var c = "aa/bb" / "/ccdd";  // => "aa/bb/ccdd"
System.println(a);
System.println(b);
System.println(c);

Result

aa/bb/ccdd
aa/bb/ccdd
aa/bb/ccdd

Example 4. Index access

Code

var a = "aa/bb";
if (a[2] == 'a'[0]) {
    System.println("a");
}
if (a[2] == '/'[0]) {
    System.println("/");
}
if (a[2] == 'b'[0]) {
    System.println("b");
}

Result

/

Example 5. Replacing sub-string

Code

var a = "abcdefghijklmnaxcabcdefghijklmnaxcabcdefghijklmnaxc";
System.println(a.replace("abc", "___"));
System.println(a.replace(/a(.)c/, "_A$1C_"));

Result

___defghijklmnaxc___defghijklmnaxc___defghijklmnaxc
_AbC_defghijklmn_AxC__AbC_defghijklmn_AxC__AbC_defghijklmn_AxC_

Example 6. Unary * operator

Code

var a = "abcdefghijklmn";
System.println(*a);
System.println(*(*a));

Result

[97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110]
abcdefghijklmn