diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 38 |
1 files changed, 37 insertions, 1 deletions
@@ -1046,7 +1046,10 @@ into the literal template. If a is bound to "apple" and b to "banana", the quasiliteral `one@a and two @{b}s` represents the string "one apple and two bananas". A backquote escaped by a backslash represents itself, and two consecutive @ characters code for a literal @. -There is no \e@ escape. +There is no \e@ escape. Quasiliterals support the full output variable +syntax. Expressions within variables substitutions follow the evaluation rules +of TXR Lisp when the quasiliteral occurs in TXR Lisp, and the rules of +the TXR pattern language when the quasiliteral occurs in the pattern language. .SS Numbers @@ -3318,6 +3321,39 @@ for the output clause. The syntax for this is @(NAME :filter <filterspec>}. The filter specification syntax is the same as in the output clause. See Output Filtering below. +Additional syntax is supported in output variables that is does not appear +in pattern matching variables. + +A square bracket index notation may be used to extract elements from a variable +which is a list, or to extract ranges. Elements are indexed from zero. This +notation is only available in brace-enclosed syntax, and looks like this: + +.IP +@{NAME[expr]) + +Extract the element at the position given by expr. + +.IP +@{NAME[expr1..expr2]) + +Extract a list of elements from the position given by expr1, up to +one position less than the position given by expr2. +The elements from the range are catenated together to form a single string, +with a separator character in between. The default character is a space. +An alternate character may be given as a string argument. + +.TP +Example: + + @(bind a ("a" "b" "c" "d")) + @(output) + @{a[1..3] "," 10} + @(end) + +The above produces the text "b,c" in a field 10 spaces wide. The [1..3] +argument extracts a range of a; the "," argument specifies an alternate +separator string, and 10 specifies the field width. + .SS The Repeat Directive The repeat directive is generates repeated text from a ``boilerplate'', |