lsbasi | Package lsbasi trying to rewrite Interpreters | Interpreter library
kandi X-RAY | lsbasi Summary
kandi X-RAY | lsbasi Summary
Package lsbasi trying to rewrite the Interpreters of the 《Let's Build A Simple Interpreter》 series by Golang.
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Top functions reviewed by kandi - BETA
- expr scans the next token .
- Reads lines from stdin
- newLexer creates a new Lexer
- newAssign returns a new assignment .
- newBinOp creates a binOp .
- newVarDecl creates a variable declaration .
- newTypeDef creates a new type definition
- newVarDef creates a variable definition .
- newBlock returns a new block .
- newProgram returns a new program .
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Trending Discussions on lsbasi
QUESTION
I'm translating code from Python to Lua, but I can't figure out what this line of code does:
results = [node]
To provide context, this is in the parser for a Pascal interpreter. I'm translating this code from a tutorial to try to wrap my head around interpreters. node is an object that represents a node in an abstract syntax tree. I'm not sure what the brackets do.
Here is the full code for the interpreter at this point in the tutorial. The line I'm looking at is 255.
...ANSWER
Answered 2021-May-02 at 03:23That creates a list of one element with just the node object. Presumably results is expected to be a list.
QUESTION
I'm following a article that was in python and I'm trying to implement the same thing but in javascript, I just don't undestrand the part when he uses getattr.
I think it's something like node.constructor.name, but I'm not sure because I don't understand how he can call visitor(node).
ANSWER
Answered 2019-Feb-07 at 11:31getattr gets an attribute (i.e. .foo) from an object, given the attribute name as a string. So getattr(o, 'foo') is equivalent to o.foo. The third argument is the default value which will be returned if the object does not have that attribute.
The equivalent in Javascript is:
QUESTION
I've been writing an lexer/parser/interpreter for my own language and so far all has been working. I've been following the examples over at Ruslan Spivak's blog (Github link to each article).
I wanted to extend my language grammar past what is written in the articles to include more operators like comparisons (<, >=, etc.) and also exponents (** or ^ in my language). I have this grammar:
ANSWER
Answered 2018-Aug-31 at 18:30The fact that your exponent function actually parses expressions should have been a red flag. In fact, what you need is an expression function which parses expressions and an exponent function which parses exponentiations.
You've also mixed up the precedences of exponentiation and multiplication (and other operations), because 2 * x ** 4 does not mean (2 * x) ** 4 (which would be 16x⁴), but rather 2 * (x ** 4). By the same token, x * 3 < 17 does not mean x * (3 < 17), which is how your grammar will parse it.
Normally the precedences for arithmetics look something like this:
QUESTION
Suppose that I want to write a tiny interpreter
that can evaluate expressions with binary operation
Plus, unary operation Negate and integer constants.
I'm currently interested only in the interpretation of the AST, so let's skip tokenization and parsing for simplicity.
In Haskell, there is a more or less canonical way to do it:
...ANSWER
Answered 2018-Apr-02 at 15:22If cleaner code is what you are looking for, I think the functools.singledispatch decorator would work in this case:
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