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Added an article about ExpressionLanguage AST #7831

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Added an article about ExpressionLanguage AST
javiereguiluz Apr 24, 2017
bc8057f
Finished the first draft of the article
javiereguiluz Apr 24, 2017
bfb54e2
Fixes and rewords
javiereguiluz May 3, 2017
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Fixes and rewords
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javiereguiluz committed May 3, 2017
commit bfb54e24703eb10359ccec8d46cd380b89da875c
16 changes: 9 additions & 7 deletions components/expression_language/ast.rst
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@@ -1,21 +1,22 @@
.. index::
single: AST; ExpressionLanguage
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I think we should at least add "Abstract Syntax Tree" to the index.

single: AST; Abstract Syntax Tree

Dumping and Manipulating the AST of Expressions
===============================================

In computer science, `AST`_ (*Abstract Syntax Trees*) is *"a tree representation
of the structure of source code written in a programming language"*.

Manipulating or inspecting the expressions created with the ExpressionLanguage
component is difficult because they are plain strings. A better approach is to
turn those expressions into an AST, which is a set of nodes that contain PHP
classes.
turn those expressions into an AST. In computer science, `AST`_ (*Abstract
Syntax Tree*) is *"a tree representation of the structure of source code written
in a programming language"*. In Symfony, a ExpressionLanguage AST is a set of
nodes that contain PHP classes representing the given expression.

Dumping the AST
---------------

Call the ``getNodes()`` method after parsing any expression to get its AST::
Call the :method:`Symfony\\Component\\ExpressionLanguage\\ExpressionLanguage::getNodes`
method after parsing any expression to get its AST::

use Symfony\Component\ExpressionLanguage\ExpressionLanguage;

Expand All @@ -34,7 +35,8 @@ Manipulating the AST
--------------------

The nodes of the AST can also be dumped into a PHP array of nodes to allow
manipulating them. Call the ``toArray()`` method to turn the AST into an array::
manipulating them. Call the :method:`Symfony\\Component\\ExpressionLanguage\\ExpressionLanguage::toArray`
method to turn the AST into an array::

// ...

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