7d0a5c0edb
* Adding support for maven assembly plugin to generate executable jar with all dependencies in built * Merge branch 'master' into issue-989 # Conflicts: # abstract-document/pom.xml # pom.xml * Adding maven assemly plugin for projects with name A * Update in format as per checkstyle, i.e. Spcae in place of tab with size of 2 * batch set - 2 having all project with B and C * issue-989 d-e-f * fixing eip pom and adding g-h-i-l-m-n Skipping naked object as it seems it doesn't have main method, will consider this at end * Adding for O and P projects Skipping Object-Mother as we don't have main method for same.
layout, title, folder, permalink, categories, tags
| layout | title | folder | permalink | categories | tags | |
|---|---|---|---|---|---|---|
| pattern | Interpreter | interpreter | /patterns/interpreter/ | Behavioral |
|
Intent
Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language.
Class diagram
Applicability
Use the Interpreter pattern when there is a language to interpret, and you can represent statements in the language as abstract syntax trees. The Interpreter pattern works best when
- the grammar is simple. For complex grammars, the class hierarchy for the grammar becomes large and unmanageable. Tools such as parser generators are a better alternative in such cases. They can interpret expressions without building abstract syntax trees, which can save space and possibly time
- efficiency is not a critical concern. The most efficient interpreters are usually not implemented by interpreting parse trees directly but by first translating them into another form. For example, regular expressions are often transformed into state machines. But even then, the translator can be implemented by the Interpreter pattern, so the pattern is still applicable
Real world examples
- java.util.Pattern
- java.text.Normalizer
- All subclasses of java.text.Format
- javax.el.ELResolver