Table of contents
Definition
An abstract syntax tree (AST) is a hierarchical tree-like structure that represents the syntax [→] of a computer language. This produced tree-like structure is used by compilers [→] and interpreters [→] to better convert code [→] into something the computer can further understand.
Use cases and Examples
Here is a mathematical example:
5+(10*2)
Now the AST of the above statement should look something like the figure below.
Figure 1
Note how we don’t care about the brackets, because what we’re saying here (reading from the root node ie: the top) is:
- The first thing we’re doing is adding something together.
- The left side of our addition is the number 5.
- The right side of our addition is the result of multiplying something.
- The left side of our multiplication is 10.
- The right side of our multiplication is 2.
With this visual breakdown, a computer can execute meaningful microinstructions and by the time it's done would have achieved the overall instruction set.
Summary
Abstract syntax trees are used to represent the structure of a program’s source code [→] for the compiler [→] or interpreter [→] to use.
ASTs are also used in transpilers thus translating the syntax of one language to another. For example when transpiling TypeScript to Javascript.
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