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author | William Joye <wjoye@cfa.harvard.edu> | 2018-12-25 19:55:50 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2018-12-25 19:55:50 (GMT) |
commit | ff51550ee89b473c63df78de6b2a413f21105687 (patch) | |
tree | bcdca927ed2a7b05c647b9a6bfdfd4a7ca5c730e /tcl8.6/doc/switch.n | |
parent | 01cbf5b15ea760408c24288ccb5cf8e0af9aa299 (diff) | |
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update tcl/tk
Diffstat (limited to 'tcl8.6/doc/switch.n')
-rw-r--r-- | tcl8.6/doc/switch.n | 186 |
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diff --git a/tcl8.6/doc/switch.n b/tcl8.6/doc/switch.n deleted file mode 100644 index 6e27f56..0000000 --- a/tcl8.6/doc/switch.n +++ /dev/null @@ -1,186 +0,0 @@ -'\" -'\" Copyright (c) 1993 The Regents of the University of California. -'\" Copyright (c) 1994-1997 Sun Microsystems, Inc. -'\" -'\" See the file "license.terms" for information on usage and redistribution -'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. -'\" -.TH switch n 8.5 Tcl "Tcl Built-In Commands" -.so man.macros -.BS -'\" Note: do not modify the .SH NAME line immediately below! -.SH NAME -switch \- Evaluate one of several scripts, depending on a given value -.SH SYNOPSIS -\fBswitch \fR?\fIoptions\fR?\fI string pattern body \fR?\fIpattern body \fR...? -.sp -\fBswitch \fR?\fIoptions\fR?\fI string \fR{\fIpattern body \fR?\fIpattern body \fR...?} -.BE -.SH DESCRIPTION -.PP -The \fBswitch\fR command matches its \fIstring\fR argument against each of -the \fIpattern\fR arguments in order. -As soon as it finds a \fIpattern\fR that matches \fIstring\fR it -evaluates the following \fIbody\fR argument by passing it recursively -to the Tcl interpreter and returns the result of that evaluation. -If the last \fIpattern\fR argument is \fBdefault\fR then it matches -anything. -If no \fIpattern\fR argument -matches \fIstring\fR and no default is given, then the \fBswitch\fR -command returns an empty string. -.PP -If the initial arguments to \fBswitch\fR start with \fB\-\fR then -they are treated as options -unless there are exactly two arguments to \fBswitch\fR (in which case the -first must the \fIstring\fR and the second must be the -\fIpattern\fR/\fIbody\fR list). -The following options are currently supported: -.TP 10 -\fB\-exact\fR -. -Use exact matching when comparing \fIstring\fR to a pattern. This -is the default. -.TP 10 -\fB\-glob\fR -. -When matching \fIstring\fR to the patterns, use glob-style matching -(i.e. the same as implemented by the \fBstring match\fR command). -.TP 10 -\fB\-regexp\fR -. -When matching \fIstring\fR to the patterns, use regular -expression matching -(as described in the \fBre_syntax\fR reference page). -.TP 10 -\fB\-nocase\fR -. -Causes comparisons to be handled in a case-insensitive manner. -.TP 10 -\fB\-matchvar\fR \fIvarName\fR -. -This option (only legal when \fB\-regexp\fR is also specified) -specifies the name of a variable into which the list of matches -found by the regular expression engine will be written. The first -element of the list written will be the overall substring of the input -string (i.e. the \fIstring\fR argument to \fBswitch\fR) matched, the -second element of the list will be the substring matched by the first -capturing parenthesis in the regular expression that matched, and so -on. When a \fBdefault\fR branch is taken, the variable will have the -empty list written to it. This option may be specified at the same -time as the \fB\-indexvar\fR option. -.TP 10 -\fB\-indexvar\fR \fIvarName\fR -. -This option (only legal when \fB\-regexp\fR is also specified) -specifies the name of a variable into which the list of indices -referring to matching substrings -found by the regular expression engine will be written. The first -element of the list written will be a two-element list specifying the -index of the start and index of the first character after the end of -the overall substring of the input -string (i.e. the \fIstring\fR argument to \fBswitch\fR) matched, in a -similar way to the \fB\-indices\fR option to the \fBregexp\fR can -obtain. Similarly, the second element of the list refers to the first -capturing parenthesis in the regular expression that matched, and so -on. When a \fBdefault\fR branch is taken, the variable will have the -empty list written to it. This option may be specified at the same -time as the \fB\-matchvar\fR option. -.TP 10 -\fB\-\|\-\fR -. -Marks the end of options. The argument following this one will -be treated as \fIstring\fR even if it starts with a \fB\-\fR. -This is not required when the matching patterns and bodies are grouped -together in a single argument. -.PP -Two syntaxes are provided for the \fIpattern\fR and \fIbody\fR arguments. -The first uses a separate argument for each of the patterns and commands; -this form is convenient if substitutions are desired on some of the -patterns or commands. -The second form places all of the patterns and commands together into -a single argument; the argument must have proper list structure, with -the elements of the list being the patterns and commands. -The second form makes it easy to construct multi-line switch commands, -since the braces around the whole list make it unnecessary to include a -backslash at the end of each line. -Since the \fIpattern\fR arguments are in braces in the second form, -no command or variable substitutions are performed on them; this makes -the behavior of the second form different than the first form in some -cases. -.PP -If a \fIbody\fR is specified as -.QW \fB\-\fR -it means that the \fIbody\fR -for the next pattern should also be used as the body for this -pattern (if the next pattern also has a body of -.QW \fB\-\fR -then the body after that is used, and so on). -This feature makes it possible to share a single \fIbody\fR among -several patterns. -.PP -Beware of how you place comments in \fBswitch\fR commands. Comments -should only be placed \fBinside\fR the execution body of one of the -patterns, and not intermingled with the patterns. -.SH "EXAMPLES" -.PP -The \fBswitch\fR command can match against variables and not just -literals, as shown here (the result is \fI2\fR): -.PP -.CS -set foo "abc" -\fBswitch\fR abc a \- b {expr {1}} $foo {expr {2}} default {expr {3}} -.CE -.PP -Using glob matching and the fall-through body is an alternative to -writing regular expressions with alternations, as can be seen here -(this returns \fI1\fR): -.PP -.CS -\fBswitch\fR \-glob aaab { - a*b \- - b {expr {1}} - a* {expr {2}} - default {expr {3}} -} -.CE -.PP -Whenever nothing matches, the \fBdefault\fR clause (which must be -last) is taken. This example has a result of \fI3\fR: -.PP -.CS -\fBswitch\fR xyz { - a \- - b { - # Correct Comment Placement - expr {1} - } - c { - expr {2} - } - default { - expr {3} - } -} -.CE -.PP -When matching against regular expressions, information about what -exactly matched is easily obtained using the \fB\-matchvar\fR option: -.PP -.CS -\fBswitch\fR \-regexp \-matchvar foo \-\- $bar { - a(b*)c { - puts "Found [string length [lindex $foo 1]] 'b's" - } - d(e*)f(g*)h { - puts "Found [string length [lindex $foo 1]] 'e's and\e - [string length [lindex $foo 2]] 'g's" - } -} -.CE -.SH "SEE ALSO" -for(n), if(n), regexp(n) -.SH KEYWORDS -switch, match, regular expression -.\" Local Variables: -.\" mode: nroff -.\" End: |