126 lines
2.9 KiB
Plaintext
126 lines
2.9 KiB
Plaintext
[[painless-literals]]
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=== Literals
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Use a literal to specify a value directly in an
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<<painless-operators, operation>>.
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[[integer-literals]]
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==== Integers
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Use an integer literal to specify an integer type value in decimal, octal, or
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hex notation of a <<primitive-types, primitive type>> `int`, `long`, `float`,
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or `double`. Use the following single letter designations to specify the
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primitive type: `l` or `L` for `long`, `f` or `F` for `float`, and `d` or `D`
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for `double`. If not specified, the type defaults to `int`. Use `0` as a prefix
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to specify an integer literal as octal, and use `0x` or `0X` as a prefix to
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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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[[float-literals]]
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==== Floats
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Use a floating point literal to specify a floating point type value of a
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<<primitive-types, primitive type>> `float` or `double`. Use the following
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single letter designations to specify the primitive type: `f` or `F` for `float`
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and `d` or `D` for `double`. If not specified, the type defaults 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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[[string-literals]]
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==== Strings
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Use a string literal to specify a <<string-type, `String` type>> value 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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[[character-literals]]
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==== Characters
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Character literals are not specified directly. Instead, use the
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<<string-character-casting, cast operator>> to convert a `String` type value
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into a `char` type value.
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