python-ast 1.0.2

A library for compiling Python to Rust
Documentation 
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use proc_macro2::TokenStream;
use pyo3::{Bound, FromPyObject, PyAny, PyResult, types::PyAnyMethods};
use quote::quote;
use serde::{Deserialize, Serialize};

use crate::{
    CodeGen, CodeGenContext, ExprType, PythonOptions, SymbolTableScopes,
    Node, impl_node_with_positions, PyAttributeExtractor, extract_list
};

use super::Statement;

#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
pub struct For {
    pub target: ExprType,
    pub iter: ExprType,
    pub body: Vec<Statement>,
    pub orelse: Vec<Statement>,
    pub lineno: Option<usize>,
    pub col_offset: Option<usize>,
    pub end_lineno: Option<usize>,
    pub end_col_offset: Option<usize>,
}

impl<'a> FromPyObject<'a> for For {
    fn extract_bound(ob: &Bound<'a, PyAny>) -> PyResult<Self> {
        let target = ob.extract_attr_with_context("target", "for loop target")?;
        let iter = ob.extract_attr_with_context("iter", "for loop iterator")?;
        
        let target = target.extract().expect("getting for target");
        let iter = iter.extract().expect("getting for iter");
        
        let body: Vec<Statement> = extract_list(ob, "body", "for body statements")?;
        let orelse: Vec<Statement> = extract_list(ob, "orelse", "for else statements")?;
        
        Ok(For {
            target,
            iter,
            body,
            orelse,
            lineno: ob.lineno(),
            col_offset: ob.col_offset(),
            end_lineno: ob.end_lineno(),
            end_col_offset: ob.end_col_offset(),
        })
    }
}

impl_node_with_positions!(For { lineno, col_offset, end_lineno, end_col_offset });

impl CodeGen for For {
    type Context = CodeGenContext;
    type Options = PythonOptions;
    type SymbolTable = SymbolTableScopes;

    fn find_symbols(self, symbols: Self::SymbolTable) -> Self::SymbolTable {
        let symbols = self.target.find_symbols(symbols);
        let symbols = self.iter.find_symbols(symbols);
        let symbols = self.body.into_iter().fold(symbols, |acc, stmt| stmt.find_symbols(acc));
        self.orelse.into_iter().fold(symbols, |acc, stmt| stmt.find_symbols(acc))
    }

    fn to_rust(
        self,
        ctx: Self::Context,
        options: Self::Options,
        symbols: Self::SymbolTable,
    ) -> Result<TokenStream, Box<dyn std::error::Error>> {
        let target = self.target.to_rust(ctx.clone(), options.clone(), symbols.clone())?;
        let iter = self.iter.to_rust(ctx.clone(), options.clone(), symbols.clone())?;
        
        let body_stmts: Result<Vec<_>, _> = self.body
            .into_iter()
            .map(|stmt| stmt.to_rust(ctx.clone(), options.clone(), symbols.clone()))
            .collect();
        let body_stmts = body_stmts?;
        
        if self.orelse.is_empty() {
            Ok(quote! {
                for #target in #iter {
                    #(#body_stmts)*
                }
            })
        } else {
            // Note: Rust doesn't have for-else, so we need to track completion
            let else_stmts: Result<Vec<_>, _> = self.orelse
                .into_iter()
                .map(|stmt| stmt.to_rust(ctx.clone(), options.clone(), symbols.clone()))
                .collect();
            let else_stmts = else_stmts?;
            
            Ok(quote! {
                {
                    let mut completed = true;
                    for #target in #iter {
                        #(#body_stmts)*
                        completed = false;
                        break;
                    }
                    if completed {
                        #(#else_stmts)*
                    }
                }
            })
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::create_parse_test;

    create_parse_test!(test_simple_for, "for x in range(10):\n    print(x)", "for_test.py");
    create_parse_test!(test_for_else, "for x in range(10):\n    print(x)\nelse:\n    print('done')", "for_test.py");
    create_parse_test!(test_for_list, "for item in [1, 2, 3]:\n    print(item)", "for_test.py");
}