computer science

Tail recursive parser

Tail recursive parser is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Tail recursive parser rather than just read about it. In short: In computer science, tail recursive parsers are a derivation from the more common recursive descent parsers. Tail recursive parsers are commonly used to parse left recursive grammars.

Key takeaways

Tail recursive parser belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Tail recursive parser to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Tail recursive parser from memory before moving on to harder problems.

Reference excerpt

In computer science, tail recursive parsers are a derivation from the more common recursive descent parsers. Tail recursive parsers are commonly used to parse left recursive grammars. They use a smaller amount of stack space than regular recursive descent parsers, given that the runtime or compilation tool has a way to optimize tail calls into jumps. They are also easy to write. Typical recursive descent parsers make parsing left recursive grammars impossible (because of an infinite loop problem). Tail recursive parsers use a node reparenting technique that makes this allowable.

Example Given an EBNF Grammar such as the following:

A simple tail recursive parser can be written much like a recursive descent parser. The typical algorithm for parsing a grammar like this using an abstract syntax tree is:

Parse the next level of the grammar and get its output tree, designate it the first tree, F While there is terminating token, T, that can be put as the parent of this node: Allocate a new node, N Set N's current operator as the current input token Advance the input one token Set N's left subtree as F Parse another level down again and store this as the next tree, X Set N's right subtree as X Set F to N Return N A basic example of this kind of parser in C is shown here. Implementation details have been omitted for simplicity.

Worked examples

Example 1 — a first encounter with Tail recursive parser

Start with the simplest possible case. Write down what Tail recursive parser claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Tail recursive parser before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Tail recursive parser ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Tail recursive parser

In research: Tail recursive parser appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Tail recursive parser in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Tail recursive parser is common in secondary-school and first-year university syllabi. It links to neighbouring topics Parsing algorithms, so understanding it makes those chapters shorter.
In everyday life: Look for Tail recursive parser outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Tail recursive parser” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Tail recursive parser in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tail recursive parser means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Tail recursive parser out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tail recursive parser in simple terms?

In computer science, tail recursive parsers are a derivation from the more common recursive descent parsers. Tail recursive parsers are commonly used to parse left recursive grammars.

Why does Tail recursive parser matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Tail recursive parser?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Tail recursive parser.