diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 50 |
1 files changed, 32 insertions, 18 deletions
@@ -604,13 +604,21 @@ current position in the data, to the end of the line. Example: .SS Variable Followed by Text -If the variable is followed by text (all non-directive material extending to -the end of the line, or to the start of another directive), then the extent of -the negative match is determined by searching for the first occurrence of that text -within the line, starting at the current position. The variable matches -everything between the current position and the matching position (not -including the matching position). Any whitespace which follows the -variable (and is not enclosed inside braces that surround the variable +For the purposes of determining the negative match, text is defined as a +sequence of literal text and regular expressions, not divided by a directive. +So for instance in this example: + + @a:@/foo/bcd e@(maybe)f@(end) + +the variable @a is considered to be followed by ":@/foo/bcd e". + +If a variable is followed by text, then the extent of the negative match is +determined by searching for the first occurrence of that text within the line, +starting at the current position. + +The variable matches everything between the current position and the matching +position (not including the matching position). Any whitespace which follows +the variable (and is not enclosed inside braces that surround the variable name) is part of the text. For example: pattern: "a b @FOO e f" @@ -624,12 +632,12 @@ is " e f". This is found within the data "c d e f" at position 3 (counting from 0). So positions 0-2 ("c d") constitute the matching text which is bound to FOO. -.SS Variable Followed by a Regular Expression, Function Call or Directive +.SS Variable Followed by a Function Call or Directive -If the variable is followed by a regular expression, function -call, or a directive, the extent is determined by scanning the text -for the first position where a match occurs for the regular expression, call or -directive. (See Regular Expressions section below, and FUNCTIONS.) +If the variable is followed by a function call, or a directive, the extent is +determined by scanning the text for the first position where a match occurs for +the regular expression, call or directive. (For a description of functions, +see FUNCTIONS.) Note that the given variable and the function or directive are considered in isolation. This means, for instance, that @var@(skip)text is a degenerate @@ -695,12 +703,18 @@ nested list, then each character string in the list is tried in turn to produce a match. The first match is taken. An unbound variable may be followed by another unbound variable which specifies -a regular expression match. This is a special case called a "double variable -match". What happens is that the text is searched using the regular -expression. If the search fails, than neither variable is bound: it is a -matching failure. If the search succeeds, than the first variable is bound to -the text which is skipped by the regular expression search. The second -variable is bound to the text matched by the regular expression. +a regular expression or function call match. This is a special case called a +"double variable match". What happens is that the text is searched using the +regular expression or function. If the search fails, than neither variable is +bound: it is a matching failure. If the search succeeds, than the first +variable is bound to the text which is skipped by the search. The second +variable is bound to the text matched by the regular expression or function. +Examples: + + pattern: "@foo@{bar /abc/}" + data: "xyz@#abc" + result: foo="xyz@#", BAR="abc" + .SS Consecutive Variables Via Directive |