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Description

The @x:Act string type is based on the Java String type and holds sequences of 16-bit characters. Unlike Java that uses reference semantics for string == equality, in @x:Act == string equality is always value equality that compares the characters in the string.

String iterators include Chars[s] and Lines[s].

Views of string include boolean, fold, date, and file.

Examples of how to use the date view can be found in the string example.

Type string

@x:type string

@x:type @x:func sys:Cat(a,b)~string
@x:type @x:func sys:Eq(a~string,b~string)~boolean
@x:type @x:func sys:Ne(a~string,b~string)~boolean
@x:type @x:func sys:Less(a~string,b~string)~boolean
@x:type @x:func sys:LessEq(a~string,b~string)~boolean
@x:type @x:func sys:Greater(a~string,b~string)~boolean
@x:type @x:func sys:GreaterEq(a~string,b~string)~boolean
@x:self @x:func sys:Init(a)~void
@x:self @x:func sys:Subscript(index)
@x:self @x:const size~int

Type Function sys:Cat

@x:func sys:Cat(a,b)~string
a first parameter
b second parameter

Semantics

The result is the string concatenation of string(a) and string(b).

Type Function sys:Eq

@x:func sys:Eq(a~string,b~string)~boolean
a first parameter
b second parameter

Semantics

If a and b have the same size and same characters, then the result is true, else the result is false.

Type Function sys:Ne

@x:func sys:Ne(a~string,b~string)~boolean
a first parameter
b second parameter

Semantics

If a and b have the same size and same characters, then the result is false, else the result is true.

Type Function sys:Less

@x:func sys:Less(a~string,b~string)~boolean
a first parameter
b second parameter

Semantics

If a is less than b, then the result is true, else the result is false.

Type Function sys:LessEq

@x:func sys:LessEq(a~string,b~string)~boolean
a first parameter
b second parameter

Semantics

If a is less than or equal to b, then the result is true, else the result is false.

Type Function sys:Greater

@x:func sys:Greater(a~string,b~string)~boolean
a first parameter
b second parameter

Semantics

If a is greater than b, then the result is true, else the result is false.

Type Function sys:GreaterEq

@x:func sys:GreaterEq(a~string,b~string)~boolean
a first parameter
b second parameter

Semantics

If a is greater than or equal to b, then the result is true, else the result is false.

Self Function sys:Init

@x:func sys:Init(a)~void
a first parameter

Semantics

There are two forms of string constructor: a special single character constructor and a general purpose string constructor.

For the special single character constructor, a should have the form code=nnn where nnn is an integer value in the range 0 to 65535. The result will be a string with a single character whose internal code was given by n.

All other cases are general purpose string constructors. If a?string then the object is initialized to
   a
otherwise the object is initialized to
   Type[a].toString()

Self Function sys:Subscript

@x:func sys:Subscript(index)
index The subscript.

Semantics

There are two kinds of string subscript: character subscript and substring.

For a character subscript of a string s, index should be an integer in the range 0 to s.size. The result will be the integer character code for the index'th character. The value will be in the range 0..65535.

For a substring of a string s, index should have the form i..j where i and j have type int. If i == j + 1 the result is the empty string (""). Otherwise we require 1 <= i & i <= j & j <= s.size. In this case the result will be the substring of s containing character in positions i through j inclusive.

Self Const size

@x:const size~int

Semantics

The number of character in the string.