OpenSearch/docs/painless/painless-lang-spec/painless-literals.asciidoc

[[painless-literals]]
=== Literals

Use a literal to specify a value directly in an
<<painless-operators, operation>>.

[[integer-literals]]
==== Integers

Use an integer literal to specify an integer type value in decimal, octal, or
hex notation of a <<primitive-types, primitive type>> `int`, `long`, `float`,
or `double`. Use the following single letter designations to specify the
primitive type: `l` or `L` for `long`, `f` or `F` for `float`, and `d` or `D`
for `double`. If not specified, the type defaults to `int`.  Use `0` as a prefix
to specify an integer literal as octal, and use `0x` or `0X` as a prefix to
specify an integer literal as hex.

*Grammar*

[source,ANTLR4]
----
INTEGER: '-'? ( '0' | [1-9] [0-9]* ) [lLfFdD]?;
OCTAL:   '-'? '0' [0-7]+ [lL]?;
HEX:     '-'? '0' [xX] [0-9a-fA-F]+ [lL]?;
----

*Examples*

* Integer literals.
+
[source,Painless]
----
0     <1>
0D    <2>
1234L <3>
-90f  <4>
-022  <5>
0xF2A <6>
----
+
<1> `int 0`
<2> `double 0.0`
<3> `long 1234`
<4> `float -90.0`
<5> `int -18` in octal
<6> `int 3882` in hex

[[float-literals]]
==== Floats

Use a floating point literal to specify a floating point type value of a
<<primitive-types, primitive type>> `float` or `double`. Use the following
single letter designations to specify the primitive type: `f` or `F` for `float`
and `d` or `D` for `double`. If not specified, the type defaults to `double`.

*Grammar*

[source,ANTLR4]
----
DECIMAL: '-'? ( '0' | [1-9] [0-9]* ) (DOT [0-9]+)? EXPONENT? [fFdD]?;
EXPONENT: ( [eE] [+\-]? [0-9]+ );
----

*Examples*

* Floating point literals.
+
[source,Painless]
----
0.0      <1>
1E6      <2>
0.977777 <3>
-126.34  <4>
89.9F    <5>
----
+
<1> `double 0.0`
<2> `double 1000000.0` in exponent notation
<3> `double 0.977777`
<4> `double -126.34`
<5> `float 89.9`

[[string-literals]]
==== Strings

Use a string literal to specify a <<string-type, `String` type>> value with
either single-quotes or double-quotes. Use a `\"` token to include a
double-quote as part of a double-quoted string literal. Use a `\'` token to
include a single-quote as part of a single-quoted string literal.  Use a `\\`
token to include a backslash as part of any string literal.

*Grammar*

[source,ANTLR4]
----
STRING: ( '"'  ( '\\"'  | '\\\\' | ~[\\"] )*? '"'  )
      | ( '\'' ( '\\\'' | '\\\\' | ~[\\'] )*? '\'' );
----

*Examples*

* String literals using single-quotes.
+
[source,Painless]
----
'single-quoted string literal'
'\'single-quoted with escaped single-quotes\' and backslash \\'
'single-quoted with non-escaped "double-quotes"'
----
+
* String literals using double-quotes.
+
[source,Painless]
----
"double-quoted string literal"
"\"double-quoted with escaped double-quotes\" and backslash: \\"
"double-quoted with non-escaped 'single-quotes'"
----

[[character-literals]]
==== Characters

Character literals are not specified directly. Instead, use the
<<string-character-casting, cast operator>> to convert a `String` type value
into a `char` type value.