Section: User Contributed Perl Documentation (3)
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Imager::Expr::Assem - an assembler for producing code for the Imager
my $expr = Imager::Expr->new(assem=>'...', ...)
This module is a simple Imager::Expr compiler that compiles a
low-level language that has a nearly 1-to-1 relationship to the
internal representation used for compiled regmach code.
Each line can contain multiple statements separated by semi-colons.
Anything after '#' in a line is ignored.
Types of statements:
- variable definition
defines variable name to have type, which can be any of 'n' or
'num' for a numeric type or 'pixel', 'p' or 'c' for a pixel or color
Variable names cannot include whitespace.
Operators can be split into 3 basic types, those that have a result
value, those that don't and the null operator, eg. jump has no value.
The format for operators that return a value is typically:
result = operator operand ...
and for those that don't return a value:
where operator is any valid regmach operator, result is any variable
defined with "var", and operands are variables, constants or
literals, or for jump operators, labels.
The set operator can be simplified to:
result = operator
All operators maybe preceded by a label, which is any non-whitespace
text immediately followed by a colon (':').
Note that the current optimizer may produce incorrect optimization for
your code, fortunately the optimizer will disable itself if you
include any jump operator in your code. A single jump to anywhere
after your final ret operator can be used to disable the optimizer
without slowing down your code.
There's currently no high-level code generation that can generate code
with loops or real conditions.
Imager(3), transform.perl, regmach.c
Tony Cook <firstname.lastname@example.org>
- SEE ALSO
linux.jgfs.net manual pages