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diff --git a/doc/switch.n b/doc/switch.n new file mode 100644 index 0000000..b2754ca --- /dev/null +++ b/doc/switch.n @@ -0,0 +1,107 @@ +'\" +'\" 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. +'\" +'\" SCCS: @(#) switch.n 1.10 97/10/31 13:05:55 +'\" +.so man.macros +.TH switch n 7.0 Tcl "Tcl Built-In Commands" +.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. 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 +(i.e. the same as implemented by the \fBregexp\fR command). +.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. +.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 ``\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 ``\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 +Below are some examples of \fBswitch\fR commands: +.CS +\fBswitch\0abc\0a\0\-\0b\0{format 1}\0abc\0{format 2}\0default\0{format 3}\fR +.CE +will return \fB2\fR, +.CS +\fBswitch\0\-regexp\0aaab { + ^a.*b$\0\- + b\0{format 1} + a*\0{format 2} + default\0{format 3} +}\fR +.CE +will return \fB1\fR, and +.CS +\fBswitch\0xyz { + a + \- + b + {format 1} + a* + {format 2} + default + {format 3} +}\fR +.CE +will return \fB3\fR. + +.SH KEYWORDS +switch, match, regular expression |