1Math::Expression::EvaluUasteorr:C:oPnatrrsiebru(t3e)d PeMralthD:o:cEuxmpernetsastiioonn::Evaluator::Parser(3)
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NAME

6       Math::Expression::Evaluator::Parser - Parse mathematical expressions
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SYNOPSIS

9           use Math::Expression::Evaluator::Parser;
10           my $exp = '2 + a * 4';
11           my $ast = Math::Expression::Evaluator::Parser::parse($exp, {});
12           # $ast is now something like this:
13           # $ast = ['+',
14           #          2,
15           #         ['*',
16           #          ['$', 'a'],
17           #          4
18           #         ]
19           #        ];
20

DESCRIPTION

22       This module parses a mathematical expression in usual notation, and
23       turns it into an Abstract Syntax Tree (AST).
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25       If you want to have a simple interface and want to evaluate these ASTs,
26       use Math::Expression::Evaluator.
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28       The following description of the AST structure matches the current
29       implementation, but really is an implementation detail that's subject
30       to change without further notice. In particular a possible addition of
31       meta information (like file and line numbers) might require a change of
32       structure.
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34       The AST is a tree that consists of nested array refs. The first item is
35       a string (until now always a single character), and denotes the type of
36       the node. The rest of the items in the array is a list of its
37       arguments.
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39       For the mathematical symbols "+", "-", "*", "/", "^" (exponentation)
40       this is straight forward, but "/" and "-" are always treated as prefix
41       ops, so the string '2 - 3' is actually turned into "['+', 2, ['-',
42       3]]".
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44       Other AST nodes are
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46       '$' "['$', $var_name]" represents a variable.
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48       '{' "['{', $expr1, $expr2, ... ]" represents a block, i.e. a list of
49           expressions.
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51       '=' "['=', $var, $expr]" represents an assignment, where $expr is
52           assigned to $var.
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54       '&' "['&', $name, @args]" is a function toll to the function called
55           $name.
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METHODS

58       parse
59           "parse" takes a string and a hash ref, where the hash ref takes
60           configuration parameters. Currently the only allowed option is
61           "force_semicolon". If set to a true value, it forces statements to
62           be forced by semicolons (so "2 3" will be forbidden, "2; 3" is
63           still allowed).
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65           "parse" throws an exception on parse errors.
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69perl v5.30.0                      2019-07M-a2t6h::Expression::Evaluator::Parser(3)
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