[FF] 2007-30-05 - The discussion evolved in [ToW Tcl on WebFreeWay] has generate some interest, and here is an effort for making a '''minimal''' template engine. I would like to use this page for collecting ideas from people. Fell free to change everything, fix bugs and revolutionize the concept - it is the purpose of the page.

Here's how it is (initially) supposed to work:

first, let's create a template file (templtest.tmpl):

 <table><%
   for {set i 0} {$i < 4} {incr i} { %>
   <tr>
     <td><%= $i %></td>
   </tr><% 
   } %>
 </table>

now run it:

 source TemplaTcl
 TemplaTcl::parse templtest.tmpl
 TemplaTcl::dump

and here's the output that gets produced:

 <table>
   <tr>
     <td>0</td>
   </tr>
   <tr>
     <td>1</td>
   </tr>
   <tr>
     <td>2</td>
   </tr>
   <tr>
     <td>3</td>
   </tr>
 </table>

----
 #!/usr/bin/env tclsh

 package require Tcl 8.2
 package require struct

 namespace eval TemplaTcl {
	variable data
	variable mode
	variable modeprev

	proc parse {file} {
		variable data
		variable mode
		variable modeprev
		set mode raw
		mode raw

		# read the template into $rawl - list of chars
		set fh [open $file r]
		set raw [read $fh]
		if {[catch {close $fh} err]} {puts "TemplaTcl: $err"}
		set rawl [split $raw {}]

		::struct::queue cc

		foreach ch $rawl {
			# we work char-by-char :|
			cc put $ch
			set sz [cc size]

			# max block to compare (<%=) is 3 chars long:
			if {$sz >= 3} {
				set s3 [join [cc peek 3] {}]
				set s2 [join [cc peek 2] {}]
				if {$mode == "raw"} {
					if {$s3 == "<%="} {
						# <%= is a shorthand for puts ...
						cc get 3
						mode code
						buf "puts -nonewline "
						continue
					} elseif {$s2 == "<%"} {
						# <% indicates begin of a code block
						cc get 2
						mode code
						continue
					}
				} elseif {$mode == "code"} {
					if {$s2 == "%>"} {
						# and %> is the end of code block
						cc get 2
						mode raw
						continue
					}
				}
				buf [cc get]
			}
		}
		# finish working on the queue:
		while {[cc size] > 0} {
			buf [cc get]
		}
		mode flush
	}

	proc mode {m} {
		# used internally by parse - switches mode and stuff...
		variable data
		variable mode
		variable modeprev

		set newm {}
		switch $m {code - raw {set newm $m}}
		if {$newm != {}} {
			set modeprev $mode
			set mode $newm
			set data(buf:$mode) {}
		}
		if {$m == "flush"} {set modeprev $mode ; set mode _}
		if {$mode != $modeprev} {
			lappend data(out) [list $modeprev $data(buf:$modeprev)]
			set data(buf:$modeprev) {}
		}
	}

	proc buf {ch} {
		# used internally by parse - put $ch in the right buffer
		variable data
		variable mode
		append data(buf:$mode) $ch
	}

	proc dump {} {
		# run the template script
		variable data
		set tclBuf ""
		foreach l $data(out) {
			set t [lindex $l 0]
			set d [lindex $l 1]
			switch $t {
				raw {append tclBuf [list puts -nonewline $d]\n}
				code {append tclBuf $d\n}
			}
		}
		eval $tclBuf
	}
 }
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''[APW] 2007-05-30'' Great idea to start with implementing something to play with!!

What about naming the page "Tcl Template Engines"? I will add a reference to your page in ToW.

[FF] Yes, I thought so ([TemplaTcl: a Tcl template engine]) but I forgot that when creating the page. :)
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[Category Application]
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