143 lines
3.3 KiB
Plaintext
143 lines
3.3 KiB
Plaintext
[[painless-literals]]
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=== Literals
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Use literals to specify different types of values directly in a script.
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[[integers]]
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==== Integers
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Use integer literals to specify an integer value in decimal, octal, or hex
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notation of the <<primitive-types, primitive types>> `int`, `long`, `float`,
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or `double`. Use the following single letter designations to specify the
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<<primitive-types, primitive type>>: `l` or `L` for `long`, `f` or `F` for
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`float`, and `d` or `D` for `double`. If not specified, the type defaults to
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`int`. Use `0` as a prefix to specify an integer literal as octal, and use
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`0x` or `0X` as a prefix to specify an integer literal as hex.
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*Grammar*
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[source,ANTLR4]
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----
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INTEGER: '-'? ( '0' | [1-9] [0-9]* ) [lLfFdD]?;
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OCTAL: '-'? '0' [0-7]+ [lL]?;
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HEX: '-'? '0' [xX] [0-9a-fA-F]+ [lL]?;
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----
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*Examples*
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* Integer literals.
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+
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[source,Painless]
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----
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<1> 0
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<2> 0D
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<3> 1234L
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<4> -90f
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<5> -022
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<6> 0xF2A
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----
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+
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<1> `int 0`
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<2> `double 0.0`
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<3> `long 1234`
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<4> `float -90.0`
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<5> `int -18` in octal
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<6> `int 3882` in hex
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[[floats]]
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==== Floats
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Use floating point literals to specify a floating point value of the
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<<primitive-types, primitive types>> `float` or `double`. Use the following
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single letter designations to specify the <<primitive-types, primitive type>>:
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`f` or `F` for `float` and `d` or `D` for `double`. If not specified, the type defaults
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to `double`.
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*Grammar*
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[source,ANTLR4]
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----
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DECIMAL: '-'? ( '0' | [1-9] [0-9]* ) (DOT [0-9]+)? EXPONENT? [fFdD]?;
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EXPONENT: ( [eE] [+\-]? [0-9]+ );
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----
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*Examples*
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* Floating point literals.
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+
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[source,Painless]
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----
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<1> 0.0
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<2> 1E6
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<3> 0.977777
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<4> -126.34
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<5> 89.9F
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----
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+
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<1> `double 0.0`
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<2> `double 1000000.0` in exponent notation
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<3> `double 0.977777`
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<4> `double -126.34`
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<5> `float 89.9`
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[[strings]]
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==== Strings
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Use string literals to specify <<string-type, String>> values with
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either single-quotes or double-quotes. Use a `\"` token to include a
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double-quote as part of a double-quoted string literal. Use a `\'` token to
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include a single-quote as part of a single-quoted string literal. Use a `\\`
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token to include a backslash as part of any string literal.
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*Grammar*
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[source,ANTLR4]
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----
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STRING: ( '"' ( '\\"' | '\\\\' | ~[\\"] )*? '"' )
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| ( '\'' ( '\\\'' | '\\\\' | ~[\\'] )*? '\'' );
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----
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*Examples*
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* String literals using single-quotes.
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[source,Painless]
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----
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'single-quoted string literal'
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'\'single-quoted with escaped single-quotes\' and backslash \\'
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'single-quoted with non-escaped "double-quotes"'
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----
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* String literals using double-quotes.
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[source,Painless]
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----
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"double-quoted string literal"
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"\"double-quoted with escaped double-quotes\" and backslash: \\"
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"double-quoted with non-escaped 'single-quotes'"
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----
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[[characters]]
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==== Characters
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Use the <<painless-casting, casting operator>> to convert string literals or
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<<string-type, String>> values into <<primitive-types, char>> values.
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<<string-type, String>> values converted into
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<<primitive-types, char>> values must be exactly one character in length
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or an error will occur.
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*Examples*
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* Casting string literals into <<primitive-types, char>> values.
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+
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[source,Painless]
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----
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(char)"C"
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(char)'c'
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----
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* Casting a <<string-type, String>> value into a <<primitive-types, char>> value.
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[source,Painless]
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----
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String s = "s";
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char c = (char)s;
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----
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