StringScanner performs lexical scanning operations on a String. Inspired by Ruby's StringScanner class
Instantiate a new StringScanner by passing its constructor the String to scan.
var ss = new StringScanner("abc123 def456");
// #<StringScanner 0/13 @ "abc12...">
For the following examples, ss represents the StringScanner instance defined above.
Returns true if the scan pointer is at the beginning of a line (right after \n) or the beginning of the String, false otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.pointer() // 0 ss.bol() // true ss.scan(/./) // "a" ss.pointer() // 1 ss.bol() // false
Returns an Array containing the contents of the capturing groups in the last evaluated pattern match.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.check(/.*(..) (..)/ // "abc123 de" ss.captures() // ["23","de"] ss.check(/\w+/) // "abc123" ss.captures() // [] ss.check(/\s+/) // null ss.captures() // []
Note: this method alters last match results
Checks if a scan of the given pattern would succeed without advancing the scan pointer. Returns the portion of the String matched on successful match, null otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.check(/[a-z]+/i) // "abc" ss.check(/[a-z]+/i) // "abc" ss.scan(/[a-z]+/i) // "abc" ss.check(/[a-z]+/i) // null ss.check(/[\d\s]+/) // "123 "
Note: this method alters last match results
Checks if a scanUntil would succeed without advancing the scan pointer. Returns the portion of the String being scanned from the scan pointer to the end of the matched String on successful match, null otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.checkUntil(/\s/) // "abc123 " ss.checkUntil(/\s/) // "abc123 " ss.checkUntil(/r/) // null ss.scanUntil(/e/) // "abc123 de" ss.checkUntil(/\s/) // null
Creates a duplicate of this instance of StringScanner.
Appends given String to the String being scanned.
ss.reset() // #<StringScanner 0/13 @ "abc12...">
ss.checkUntil(/h/) // null
ss.concat(" ghi789") // #<StringScanner 0/20 @ "abc12..."
ss.checkUntil(/h/) // "abc123 def456 gh"
Returns true if scan pointer is at the end of the String being scanned, false otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.pointer() // 0 ss.eos() // false ss.scan(/.*/) // "abc123 def456" ss.pointer() // 13 ss.eos() // true
Note: this method alters last match results
Warning: this method may return 0 on a successful operation. Use === comparision to null for failure check, for example: ss.exists(/a/i)===null
Checks if given pattern matches anywhere after the current scan pointer. This will determine if a scanUntil operation will succeed. Returns number of characters between the scan pointer and the position in which the match was found on success, null otherwise.
ss.reset() // ---- ss.exists(/c/) // 2 ss.match() // "c" ss.matched() // true // ---- ss.exists(/a/) // 0 ss.match() // "a" ss.matched() // true // ---- ss.exists(/b*/) // 0 ss.match() // "" ss.matched() // true // ---- ss.exists(/m/) // null ss.match() // null ss.matched() // false
Note: this method alters last match results
Note: Ruby equivalent: get_byte
scans one character and returns it; exactly equal to scan(/./).
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.getch() // "a" ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scan(/./) // "a"
Note: Ruby equivalent: matched
Returns the last String matched or null if the last attempted match failed.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scan(/[a-z]+/i) // "abc" ss.match() // "abc" ss.check(/[a-z]+/i) // null ss.match() // null
Note: Ruby equivalent: match?
Checks if a scan of the given pattern would succeed without advancing the scan pointer. Returns the length of the String matched on successful match, null otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.matches(/[a-z]+/i) // 3 ss.matches(/[a-z]+/i) // 3 ss.scan(/[a-z]+/i) // "abc" ss.matches(/[a-z]+/i) // null ss.matches(/[\d\s]+/) // 4
Note: Ruby equivalent: matched?
Returns true if the last attempted match was successful, false otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scan(/\w+/) // "abc123" ss.matched() // true ss.scan(/\w+/) // null ss.matched() // false
Warning: this method may return 0 on a successful operation. Use === comparision to null for failure check, for example: ss.matchSize()===null
Returns the length of the most recently matched String if the most recent match attempt succeeded, null otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scan(/\w+/) // "abc123" ss.matchSize() // 6 ss.check(/\w*/) // "" ss.matchSize() // 0 ss.check(/\w+/) // null ss.matchSize() // null
Returns len characters after the scan pointer, or the rest of the String, whichever is shorter.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scan(/.*d/) // "abc123 d" ss.peek(3) // "ef4" ss.peek(9001) // "ef456" ss.peek(0) // "" ss.peek(-3) // ""
Returns the scan pointer position as an integer.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.pointer() // 0 ss.scan(/\w+\d+\s+/) // "abc123 " ss.pointer() // 7 ss.scan([a-z]+) // "def" ss.pointer() // 10
Manually move the scan pointer to pos characters from the beginning of the String. The scan pointer is bounded between zero and the scanning String's length. Returns position to which the scan pointer was moved. setPointer does not reset nor modify the last match results.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.setPointer(4) // 4 ss.scan(/\d+/) // "23" ss.pointer() // 6 ss.setPointer(-4) // 0 ss.setPointer(99) // 13
Moves the scan pointer back to the beginning of the String being scanned and clears the last match results.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scanUntil(/(\s)/) // "abc123 " ss.pointer() // 7 ss.match() // "abc123 " ss.captures() // [" "] ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.pointer() // 0 ss.match() // null ss.captures() // []
Returns the portion of the String being scanned after the scan pointer.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scanUntil(/\s/) // "abc123 " ss.rest() // "def456"
Note: this method alters last match results
Attempts to match the given pattern at the position of the scan pointer. Returns the matched String and advances the String pointer upon successful match. A failed match will result in a null value being returned.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scan(/[a-z]+/) // "abc" ss // #<StringScanner 3/13 @ "abc12..."> ss.scan(/[a-z]+/) // null ss // #<StringScanner 3/13 @ "abc12..."> ss.scan(/[0-9]+/) // "123" ss // #<StringScanner 6/13 @ "abc12...">
Note: this method alters last match results
Attempts to match the pattern against the String being scanned. On a successful match, the scan pointer is advanced to the end of the matched portion of the String and the portion of the String being scanned up to and including the matched String is returned. On a failed match, null is returned.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.scanUntil(/ /) // "abc123 " ss.scanUntil(/f/) // "def" ss.scanUntil(/f/) // null
Note: this method alters last match results
Performs a scan, returning the length of the matched String on successful match, null otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.skip(/[a-z]+/) // 3 ss.skip(/[a-z]+/) // null ss.skip(/[0-9]+/) // 3
Note: this method alters last match results
Performs a scanUntil, returning the length of the matched String on successful match, null otherwise.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.skipUntil(/ /) // 7 ss.skipUntil(/f/) // 3 ss.skipUntil(/f/) // null
Returns the entire String being scanned.
ss.string() // "abc123 def456" ss.getch() // "a" ss.string() // "abc123 def456"
Advances the scan pointer to the end of the String being scanned and resets the last match results.
ss.reset() // #<StringScanner 0/13 @ "abc12..."> ss.getch() // "a" ss.pointer() // 1 ss.terminate() // #<StringScanner fin> ss.pointer() // 13 ss.eos() // true ss.match() // null
Not really an issue, but StringScanner assumes the global flag (g) is disabled on any RegExp objects passed as patterns to any of its methods. If the global flag is enabled, StringScanner may produce unexpected results.
I am always open for feature requests or any feedback. I can be reached at Github.
Thanks to the Ruby community for the original idea and implementation.
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Found a bug in this plugin? Please report it this repository's Github Issues.
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