ELI5: pratt parser
// explanation
What is a Pratt parser?
A Pratt parser is a way to teach a computer to read and understand mathematical expressions like "2 + 3 * 4" [2]. Instead of checking every possible rule for how operations should be ordered, it looks at each piece (called a token) one at a time and figures out what to do based on what it sees [3].
Why do we need it?
When you write math or code, some operations need to happen before others - like multiplication before addition [2]. A Pratt parser is really good at handling these rules, and it's much simpler to write than other methods [1].
How is it different from other parsers?
Most parsers check every level of importance for operations, like checking for addition, then multiplication, then parentheses [3]. A Pratt parser is smarter - it just looks at the next piece of information and decides what to do based on that one piece [3].
When would you use it?
Programmers use Pratt parsers when they're building interpreters or compilers - basically tools that read code or expressions and understand them [6].
// sources
Apr 13, 2020 ... The simplest technique for hand-writing a parser is recursive descent, which models the grammar as a set of mutually recursive functions.
Mar 19, 2011 ... Pratt parsing is the jelly. When you mix the two together, you get a simple, terse, readable parser that can handle any grammar you throw at it.
Feb 9, 2022 ... A Pratt parser dispatches on the next token, instead of recursing down the N precedence levels. In the end it's not all that different.
Operator-precedence parser · Contents · Relationship to other parsers · Precedence climbing method · Pratt parsing · Alternative methods · References · External links.
Aug 11, 2017 ... Pratt parsing works by scanning the input tokens, and classifying them into two categories ... operators that operate to the right, with no left- ...
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