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fce1bbc20e
Drops the inline callouts from the painless reference book. These callouts are incompatible with Asciidoctor and we'd very much like to switch to Asciidoctor for building this book, partially because Asciidoctor is actively developed and AsciiDoc is not, and partially because it builds the book three times faster.
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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0 <1>
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0D <2>
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1234L <3>
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-90f <4>
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-022 <5>
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0xF2A <6>
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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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0.0 <1>
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1E6 <2>
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0.977777 <3>
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-126.34 <4>
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89.9F <5>
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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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+
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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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+
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* String literals using double-quotes.
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+
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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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