juneau-doc/docs/Topics/05.juneau-config/03.Variables/01.LogicVariables.html

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Logic Variables

<p>
	The default variable resolver also provides the following logic variables for performing simple logical operations:
</p>
<ul class='javatree'>
	<li class='jc'>{@link oaj.svl.vars.IfVar} - <c>$IF{arg,then[,else]}</c>
	<li class='jc'>{@link oaj.svl.vars.SwitchVar} - <c>$SW{arg,pattern1:then1[,pattern2:then2...]}</c>
	<li class='jc'>{@link oaj.svl.vars.CoalesceVar} - <c>$CO{arg1[,arg2...]}</c>
	<li class='jc'>{@link oaj.svl.vars.PatternMatchVar} - <c>$PM{arg,pattern}</c> 
	<li class='jc'>{@link oaj.svl.vars.NotEmptyVar} - <c>$NE{arg}</c>
	<li class='jc'>{@link oaj.svl.vars.UpperCaseVar} - <c>$UC{arg}</c>
	<li class='jc'>{@link oaj.svl.vars.LowerCaseVar} - <c>$LC{arg}</c>
</ul>
<p>
	The <c>$IF</c> variable can be used for simple if/else logic:
</p>
<p class='bpcode w800'>
	<cc># Value set to 'foo' if myBooleanProperty is true</cc>
	<ck>key1</ck> = 
		<cv>$IF{		
			$S{myBooleanProperty},
			foo
		}</cv>		
			
	<cc># Value set to 'foo' if myBooleanProperty is true, 'bar' if false.</cc>
	<ck>key2</ck> = 
		<cv>$IF{		
			$S{myBooleanProperty},
			foo,
			bar
		}</cv>		

	<cc># Value set to key1 value if myBooleanProperty is true, key2 value if false.</cc>
	<ck>key3</ck> = 
		<cv>$IF{		
			$S{myBooleanProperty},
			$C{key1},
			$C{key2}
		}</cv>		
</p>
<p>
	The <c>$SW</c> variable can be used for switch blocks based on pattern matching:
</p>
<p class='bpcode w800'>
	<cc># Shell command depends on the OS</cc>
	<ck>shellCommand</ck> = 
		<cv>$SW{		
			$LC{$S{os.name}},
			*win*: bat,
			linux: bash,
			*: sh
		}</cv>		
</p>
<p>
	The <c>$CO</c> variable can be used for coalescing of values (finding the first non-null/empty match):
</p>
<p class='bpcode w800'>
	<cc># Debug flag can be enabled by system property or environment variable.</cc>
	<ck>debug</ck> = 
		<cv>$CO{		
			$S{debug},
			$E{DEBUG},
			false
		}</cv>		
</p>
<p>
	The <c>$PM</c> variable can be used for calculating boolean values:
</p>
<p class='bpcode w800'>
	<cc># Debug flag can be enabled by system property or environment variable.</cc>
	<ck>isWindows</ck> = 
		<cv>$PM{		
			$LC{$S{os.name}},
			*win*
		}</cv>		
</p>