diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 51 |
1 files changed, 45 insertions, 6 deletions
@@ -54814,8 +54814,8 @@ and .desc The .code pic -macro provides a notation for constructing a character string under the -control of +macro ("picture based formatting") provides a notation for constructing a +character string under the control of .meta format-string which indicates the insertion of zero or more .meta format-arg @@ -54823,7 +54823,7 @@ argument values. Like the .code fmt -function or quasistring syntax, the +function or quasiliteral syntax, the .code pic macro returns a character string. @@ -54837,7 +54837,12 @@ notation is different from quasiliterals or from The .code pic .meta format-string -is scanned left to right in search of +argument isn't an evaluated expression, but syntax. It must be either a string +literal or else a string quasiliteral. No other syntax is permitted. + +If +.meta pic +is a string, is scanned left to right in search of .IR "pic patterns" . Any characters not belonging to a pic pattern are copied into the output string verbatim. When a pic pattern is found, it is removed from @@ -54850,11 +54855,43 @@ When the .meta format-string is exhausted, the constructed string is returned. +If +.meta format-string +is a quasiliteral, then all of the text strings embedded within the +quasiliteral are examined in the same way, in left to right order. Each such +string is transformed into an expression which produces a character string +according to the semantics of the pic patterns it contains, and the resulting +expressions are substituted into the original quasiliteral to produce a +transformed quasiliteral. + There must be exactly as many .meta format-arg arguments as there are pic patterns in .metn format-string . +The +.code pic +macro arranges for the left-to-right evaluation of the +.meta format-arg +expressions. If +.meta format-string +is a quasiliteral, the evaluation of these expressions is interleaved +into the quasiliterals expressions and variables, in the order implied +by the placement of the corresponding pic patterns relative to the +quasiliteral elements. For instance, if +.meta format-string +is +.code `@(abc)<<<@(xyz)` +then the function +.code abc +is called first, then the +.meta format-argument +is evaluated which produces a value for the +.code <<< +pic pattern, after which the +.code xyz +function is called. + There are two kinds of pic patterns: alignment patterns, numeric patterns and escape patterns. @@ -54891,8 +54928,10 @@ field width, it is centered slightly to the left: one less space appears on its left side in respect to its right side. .RE .IP -The numeric patterns are more complex. They conform to one of the two -following syntactic rule: +The numeric patterns, by means of their visual pattern and several optional +prefix codes, specify the parameters for the conversion of a numeric +argument, which is rendered right-aligned in a fixed-width field. Numeric +patterns conform to one of the two following syntactic rule: .mono .mets <> [ sign ] [0] {#}+ >> [ point {#}+ | !] |