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Diffstat (limited to 'doc/gawktexi.in')
| -rw-r--r-- | doc/gawktexi.in | 174 |
1 files changed, 138 insertions, 36 deletions
diff --git a/doc/gawktexi.in b/doc/gawktexi.in index 95606cf3..b1eca3ba 100644 --- a/doc/gawktexi.in +++ b/doc/gawktexi.in @@ -749,6 +749,8 @@ particular records in a file and perform operations upon them. * Arrays Summary:: Summary of arrays. * Built-in:: Summarizes the built-in functions. * Calling Built-in:: How to call built-in functions. +* Boolean Functions:: A function that returns Boolean + values. * Numeric Functions:: Functions that work with numbers, including @code{int()}, @code{sin()} and @code{rand()}. @@ -856,6 +858,7 @@ particular records in a file and perform operations upon them. * Programs Summary:: Summary of programs. * Programs Exercises:: Exercises. * Nondecimal Data:: Allowing nondecimal input data. +* Boolean Typed Values:: Values with @code{bool} type. * Array Sorting:: Facilities for controlling array traversal and sorting arrays. * Controlling Array Traversal:: How to use PROCINFO["sorted_in"]. @@ -16653,7 +16656,8 @@ Any index with a non-numeric value will end up positioned as if it were zero. Order by element values in ascending order (rather than by indices). Ordering is by the type assigned to the element (@pxref{Typing and Comparison}). -All numeric values come before all string values, +All Boolean values come before all numeric values (@pxref{Boolean Typed Values}), +and all numeric values come before all string values, which in turn come before all subarrays. (Subarrays have not been described yet; @pxref{Arrays of Arrays}.) @@ -17448,6 +17452,7 @@ but are summarized here for your convenience. @menu * Calling Built-in:: How to call built-in functions. +* Boolean Functions:: A function that returns Boolean values. * Numeric Functions:: Functions that work with numbers, including @code{int()}, @code{sin()} and @code{rand()}. * String Functions:: Functions for string manipulation, such as @@ -17517,6 +17522,25 @@ and 12. But if the order of evaluation is right to left, @code{i} first becomes 10, then 11, and @code{atan2()} is called with the two arguments 11 and 10. + +@node Boolean Functions +@subsection Generating Boolean Values +@cindex boolean function + +This function is specific to @command{gawk}. It is not +available in compatibility mode (@pxref{Options}): + +@c @asis for docbook +@table @asis +@item @code{bool(@var{expression})} +@cindexgawkfunc{bool} +Return a Boolean-typed value based on the regular Boolean value +of @var{expression}. Boolean ``true'' values have numeric value one +and string value @code{"TRUE"}. Boolean ``false'' values have numeric +zero and string value @code{"FALSE"}. This is discussed in more +detail in @ref{Boolean Typed Values}. +@end table + @node Numeric Functions @subsection Numeric Functions @cindex numeric @subentry functions @@ -19804,6 +19828,9 @@ Return one of the following strings, depending upon the type of @var{x}: @item "array" @var{x} is an array. +@item "bool" +@var{x} is a Boolean typed value (@pxref{Boolean Typed Values}). + @item "regexp" @var{x} is a strongly typed regexp (@pxref{Strong Regexp Constants}). @@ -20688,7 +20715,7 @@ being aware of them. @cindex pointers to functions @cindex differences in @command{awk} and @command{gawk} @subentry indirect function calls -This section describes an advanced, @command{gawk}-specific extension. +This @value{SECTION} describes an advanced, @command{gawk}-specific extension. Often, you may wish to defer the choice of function to call until runtime. For example, you may have different kinds of records, each of which @@ -28267,6 +28294,7 @@ discusses the ability to dynamically add new built-in functions to @menu * Nondecimal Data:: Allowing nondecimal input data. +* Boolean Typed Values:: Values with @code{bool} type. * Array Sorting:: Facilities for controlling array traversal and sorting arrays. * Two-way I/O:: Two-way communications with another process. @@ -28333,6 +28361,48 @@ leads to less surprising results. This option may disappear in a future version of @command{gawk}. @end quotation +@node Boolean Typed Values +@section Boolean Typed Values + +Scalar values in @command{awk} are either numbers or strings. +@command{gawk} also supports values of type @code{regexp} +(@pxref{Strong Regexp Constants}). + +As described in @ref{Truth Values}, Boolean values in @command{awk} +don't have a separate type: a value counts as ``true'' if it is nonzero +or non-null, and as ``false'' otherwise. + +When interchanging data with languages that do have a real Boolean type, +using a standard format such as JSON or XML, the lack of a true Boolean +type in @command{awk} is problematic. +(See, for example, the @code{json} extension provided by +@uref{https://sourceforge.net/projects/gawkextlib, the @code{gawkextlib} project}.) + +It's easy to import Boolean data into @command{awk}, but then the fact +that it was originally Boolean is lost. Exporting data is even harder; +there's no way to indicate that a value is really Boolean. + +To solve this problem, @command{gawk} provides a function named @code{bool()}. +It takes one argument, which is any @command{awk} expression, and it +returns a value of Boolean type. + +The returned values are different than normal @command{awk} values. When +treated as numbers, they are either one or zero, depending upon the truth +value of the original expression passed in the call to @code{bool()}. When +treated as strings, they are either @code{"TRUE"} or @code{"FALSE"}, +again depending upon the truth value of the expression passed in the +call to @code{bool()}. The value for ``false'' is thus unusual; it is +zero numerically, but not empty when treated as a string. + +The @code{typeof()} function (@pxref{Type Functions}) returns +@code{"bool"} for these values. + +While it would have been possible to add two new built-in variables +of Boolean type named @code{TRUE} and @code{FALSE}, doing so would +undoubtedly have broken many existing @command{awk} programs. Instead, +having a ``generator'' function that creates Boolean values gives +flexibility, without breaking any existing code. + @node Array Sorting @section Controlling Array Traversal and Array Sorting @@ -34429,7 +34499,8 @@ multibyte encoding. @itemx @ @ @ @ AWK_STRNUM, @itemx @ @ @ @ AWK_ARRAY, @itemx @ @ @ @ AWK_SCALAR,@ @ @ @ @ @ @ @ @ /* opaque access to a variable */ -@itemx @ @ @ @ AWK_VALUE_COOKIE@ @ @ @ /* for updating a previously created value */ +@itemx @ @ @ @ AWK_VALUE_COOKIE,@ @ @ /* for updating a previously created value */ +@itemx @ @ @ @ AWK_BOOL @itemx @} awk_valtype_t; This @code{enum} indicates the type of a value. It is used in the following @code{struct}. @@ -34442,6 +34513,7 @@ It is used in the following @code{struct}. @itemx @ @ @ @ @ @ @ @ awk_array_t@ @ @ @ @ @ @ @ a; @itemx @ @ @ @ @ @ @ @ awk_scalar_t@ @ @ @ @ @ @ scl; @itemx @ @ @ @ @ @ @ @ awk_value_cookie_t@ vc; +@itemx @ @ @ @ @ @ @ @ awk_bool_t@ @ @ @ @ @ @ @ @ b; @itemx @ @ @ @ @} u; @itemx @} awk_value_t; An ``@command{awk} value.'' @@ -34457,6 +34529,7 @@ The @code{val_type} member indicates what kind of value the @itemx #define array_cookie@ @ @ u.a @itemx #define scalar_cookie@ @ u.scl @itemx #define value_cookie@ @ @ u.vc +@itemx #define bool_value@ @ @ @ @ u.b Using these macros makes accessing the fields of the @code{awk_value_t} more readable. @@ -34784,6 +34857,11 @@ the regular expression of length @code{len}. It expects @code{string} to be a @samp{char *} value pointing to data previously obtained from @code{gawk_malloc()}, @code{gawk_calloc()}, or @code{gawk_realloc()}. +@item static inline awk_value_t * +@itemx make_bool(awk_bool_t boolval, awk_value_t *result); +This function creates a boolean value in the @code{awk_value_t} variable +pointed to by @code{result}. + @end table @node API Ownership of MPFR and GMP Values @@ -35584,7 +35662,8 @@ value type, as appropriate. This behavior is summarized in <colspec colname="c6"/> <colspec colname="c7"/> <colspec colname="c8"/> - <spanspec spanname="hspan" namest="c3" nameend="c8" align="center"/> + <colspec colname="c9"/> + <spanspec spanname="hspan" namest="c3" nameend="c9" align="center"/> <thead> <row><entry></entry><entry spanname="hspan"><para>Type of Actual Value</para></entry></row> <row> @@ -35594,6 +35673,7 @@ value type, as appropriate. This behavior is summarized in <entry><para>Strnum</para></entry> <entry><para>Number</para></entry> <entry><para>Regex</para></entry> + <entry><para>Bool</para></entry> <entry><para>Array</para></entry> <entry><para>Undefined</para></entry> </row> @@ -35606,6 +35686,7 @@ value type, as appropriate. This behavior is summarized in <entry><para>String</para></entry> <entry><para>String</para></entry> <entry><para>String</para></entry> + <entry><para>String</para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> </row> @@ -35618,6 +35699,7 @@ value type, as appropriate. This behavior is summarized in <entry><para>false</para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> + <entry><para>false</para></entry> </row> <row> <entry></entry> @@ -35626,6 +35708,7 @@ value type, as appropriate. This behavior is summarized in <entry><para>Number</para></entry> <entry><para>Number</para></entry> <entry><para>false</para></entry> + <entry><para>Number</para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> </row> @@ -35634,6 +35717,7 @@ value type, as appropriate. This behavior is summarized in <entry><para><emphasis role="bold">Regex</emphasis></para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> + <entry><para>false</para></entry> <entry><para>Regex</para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> @@ -35641,11 +35725,23 @@ value type, as appropriate. This behavior is summarized in </row> <row> <entry><para><emphasis role="bold">Requested</emphasis></para></entry> + <entry><para><emphasis role="bold">Bool</emphasis></para></entry> + <entry><para>false</para></entry> + <entry><para>false</para></entry> + <entry><para>false</para></entry> + <entry><para>false</para></entry> + <entry><para>Bool</para></entry> + <entry><para>false</para></entry> + <entry><para>false</para></entry> + </row> + <row> + <entry><para></para></entry> <entry><para><emphasis role="bold">Array</emphasis></para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> + <entry><para>false</para></entry> <entry><para>Array</para></entry> <entry><para>false</para></entry> </row> @@ -35656,6 +35752,7 @@ value type, as appropriate. This behavior is summarized in <entry><para>Scalar</para></entry> <entry><para>Scalar</para></entry> <entry><para>Scalar</para></entry> + <entry><para>Scalar</para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> </row> @@ -35666,6 +35763,7 @@ value type, as appropriate. This behavior is summarized in <entry><para>Strnum</para></entry> <entry><para>Number</para></entry> <entry><para>Regex</para></entry> + <entry><para>Bool</para></entry> <entry><para>Array</para></entry> <entry><para>Undefined</para></entry> </row> @@ -35678,6 +35776,7 @@ value type, as appropriate. This behavior is summarized in <entry><para>false</para></entry> <entry><para>false</para></entry> <entry><para>false</para></entry> + <entry><para>false</para></entry> </row> </tbody> </tgroup> @@ -35694,43 +35793,46 @@ value type, as appropriate. This behavior is summarized in \vglue-1.1\baselineskip @end tex @c @multitable @columnfractions .166 .166 .198 .15 .15 .166 -@multitable {Requested} {Undefined} {Number} {Number} {Scalar} {Regex} {Array} {Undefined} -@headitem @tab @tab String @tab Strnum @tab Number @tab Regex @tab Array @tab Undefined -@item @tab @b{String} @tab String @tab String @tab String @tab String @tab false @tab false -@item @tab @b{Strnum} @tab false @tab Strnum @tab Strnum @tab false @tab false @tab false -@item @tab @b{Number} @tab Number @tab Number @tab Number @tab false @tab false @tab false -@item @b{Type} @tab @b{Regex} @tab false @tab false @tab false @tab Regex @tab false @tab false -@item @b{Requested} @tab @b{Array} @tab false @tab false @tab false @tab false @tab Array @tab false -@item @tab @b{Scalar} @tab Scalar @tab Scalar @tab Scalar @tab Scalar @tab false @tab false -@item @tab @b{Undefined} @tab String @tab Strnum @tab Number @tab Regex @tab Array @tab Undefined -@item @tab @b{Value cookie} @tab false @tab false @tab false @tab false @tab false @tab false +@multitable {Requested} {Undefined} {Number} {Number} {Scalar} {Regex} {Number} {Array} {Undefined} +@headitem @tab @tab String @tab Strnum @tab Number @tab Regex @tab Bool @tab Array @tab Undefined +@item @tab @b{String} @tab String @tab String @tab String @tab String @tab String @tab false @tab false +@item @tab @b{Strnum} @tab false @tab Strnum @tab Strnum @tab false @tab false @tab false @tab false +@item @tab @b{Number} @tab Number @tab Number @tab Number @tab false @tab Number @tab false @tab false +@item @b{Type} @tab @b{Regex} @tab false @tab false @tab false @tab Regex @tab false @tab false @tab false +@item @b{Requested} @tab @b{Bool} @tab false @tab false @tab false @tab false @tab Bool @tab false @tab false +@item @tab @b{Array} @tab false @tab false @tab false @tab false @tab false @tab Array @tab false +@item @tab @b{Scalar} @tab Scalar @tab Scalar @tab Scalar @tab Scalar @tab Scalar @tab false @tab false +@item @tab @b{Undefined} @tab String @tab Strnum @tab Number @tab Regex @tab Bool @tab Array @tab Undefined +@item @tab @b{Value cookie} @tab false @tab false @tab false @tab false @tab false @tab false @tab false @end multitable @end ifnotdocbook @end ifnotplaintext @ifplaintext @verbatim - +-------------------------------------------------------+ - | Type of Actual Value: | - +--------+--------+--------+--------+-------+-----------+ - | String | Strnum | Number | Regex | Array | Undefined | -+-----------+-----------+--------+--------+--------+--------+-------+-----------+ -| | String | String | String | String | String | false | false | -| +-----------+--------+--------+--------+--------+-------+-----------+ -| | Strnum | false | Strnum | Strnum | false | false | false | -| +-----------+--------+--------+--------+--------+-------+-----------+ -| | Number | Number | Number | Number | false | false | false | -| +-----------+--------+--------+--------+--------+-------+-----------+ -| | Regex | false | false | false | Regex | false | false | -| Type +-----------+--------+--------+--------+--------+-------+-----------+ -| Requested | Array | false | false | false | false | Array | false | -| +-----------+--------+--------+--------+--------+-------+-----------+ -| | Scalar | Scalar | Scalar | Scalar | Scalar | false | false | -| +-----------+--------+--------+--------+--------+-------+-----------+ -| | Undefined | String | Strnum | Number | Regex | Array | Undefined | -| +-----------+--------+--------+--------+--------+-------+-----------+ -| | Value | false | false | false | false | false | false | -| | Cookie | | | | | | | -+-----------+-----------+--------+--------+--------+--------+-------+-----------+ + +----------------------------------------------------------------+ + | Type of Actual Value: | + +--------+--------+--------+--------+--------+-------+-----------+ + | String | Strnum | Number | Regex | Bool | Array | Undefined | ++-----------+-----------+--------+--------+--------+--------+--------+-------+-----------+ +| | String | String | String | String | String | String | false | false | +| +-----------+--------+--------+--------+--------+--------+-------+-----------+ +| | Strnum | false | Strnum | Strnum | false | false | false | false | +| +-----------+--------+--------+--------+--------+--------+-------+-----------+ +| | Number | Number | Number | Number | false | Number | false | false | +| +-----------+--------+--------+--------+--------+--------+-------+-----------+ +| | Regex | false | false | false | Regex | false | false | false | +| +-----------+--------+--------+--------+--------+--------+-------+-----------+ +| Type | Bool | false | false | false | false | Bool | false | false | +| Requested +-----------+--------+--------+--------+--------+--------+-------+-----------+ +| | Array | false | false | false | false | false | Array | false | +| +-----------+--------+--------+--------+--------+--------+-------+-----------+ +| | Scalar | Scalar | Scalar | Scalar | Scalar | Scalar | false | false | +| +-----------+--------+--------+--------+--------+--------+-------+-----------+ +| | Undefined | String | Strnum | Number | Regex | Bool | Array | Undefined | +| +-----------+--------+--------+--------+--------+--------+-------+-----------+ +| | Value | false | false | false | false | false | false | false | +| | Cookie | | | | | | | | ++-----------+-----------+--------+--------+--------+--------+--------+-------+-----------+ @end verbatim @end ifplaintext @end float |