public final class UnifiedJEXL.Template extends java.lang.Object
The source text is parsed considering each line beginning with '$$' (as default pattern) as JEXL script code and all others as Unified JEXL expressions; those expressions will be invoked from the script during evaluation and their output gathered through a writer. It is thus possible to use looping or conditional construct "around" expressions generating output.
For instance:
$$ for(var x : [1, 3, 5, 42, 169]) { $$ if (x == 42) { Life, the universe, and everything $$ } else if (x > 42) { The value $(x} is over fourty-two $$ } else { The value ${x} is under fourty-two $$ } $$ }
Will evaluate as:
The value 1 is under fourty-two The value 3 is under fourty-two The value 5 is under fourty-two Life, the universe, and everything The value 169 is over fourty-two
During evaluation, the template context exposes its writer as '$jexl' which is safe to use in this case. This allows writing directly through the writer without adding new-lines as in:
$$ for(var cell : cells) { $jexl.print(cell); $jexl.print(';') }
A template is expanded as one JEXL script and a list of UnifiedJEXL expressions; each UnifiedJEXL expression being replace in the script by a call to jexl:print(expr) (the expr is in fact the expr number in the template). This integration uses a specialized JexlContext (TemplateContext) that serves as a namespace (for jexl:) and stores the expression array and the writer (java.io.Writer) that the 'jexl:print(...)' delegates the output generation to.
Constructor and Description |
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Template(java.lang.String directive,
java.io.Reader reader,
java.lang.String... parms)
Creates a new template from an input.
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Modifier and Type | Method and Description |
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java.lang.String |
asString()
Recreate the template source from its inner components.
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void |
evaluate(JexlContext context,
java.io.Writer writer)
Evaluates this template.
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void |
evaluate(JexlContext context,
java.io.Writer writer,
java.lang.Object... args)
Evaluates this template.
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UnifiedJEXL.Template |
prepare(JexlContext context)
Prepares this template by expanding any contained deferred expression.
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java.lang.String |
toString() |
public Template(java.lang.String directive, java.io.Reader reader, java.lang.String... parms)
directive
- the prefix for lines of code; can not be "$", "${", "#" or "#{"
since this would preclude being able to differentiate directives and UnifiedJEXL expressionsreader
- the input readerparms
- the parameter namesjava.lang.NullPointerException
- if either the directive prefix or input is nulljava.lang.IllegalArgumentException
- if the directive prefix is invalidpublic java.lang.String toString()
toString
in class java.lang.Object
public java.lang.String asString()
public UnifiedJEXL.Template prepare(JexlContext context)
context
- the context to prepare againstpublic void evaluate(JexlContext context, java.io.Writer writer)
context
- the context to use during evaluationwriter
- the writer to use for outputpublic void evaluate(JexlContext context, java.io.Writer writer, java.lang.Object... args)
context
- the context to use during evaluationwriter
- the writer to use for outputargs
- the arguments