Oak Fortran Parser

High-performance incremental Fortran parser for the oak ecosystem with flexible configuration, optimized for code analysis and compilation.

🎯 Overview

Oak Fortran is a robust parser for Fortran, designed to handle complete Fortran syntax including modern features. Built on the solid foundation of oak-core, it provides both high-level convenience and detailed AST generation for static analysis and code generation.

✨ Features

• Complete Fortran Syntax: Supports all Fortran features including modern specifications
• Full AST Generation: Generates comprehensive Abstract Syntax Trees
• Lexer Support: Built-in tokenization with proper span information
• Error Recovery: Graceful handling of syntax errors with detailed diagnostics

🚀 Quick Start

Basic example:

use oak_fortran::{Parser, FortranLanguage, SourceText};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let parser = Parser::new();
    let source = SourceText::new(r#"
program hello
    print *, "Hello, Fortran!"
end program hello
    "#);
    
    let result = parser.parse(&source);
    println!("Parsed Fortran successfully.");
    Ok(())
}

📋 Parsing Examples

Program Parsing

use oak_fortran::{Parser, FortranLanguage, SourceText};

let parser = Parser::new();
let source = SourceText::new(r#"
program calculator
    implicit none
    real :: a, b, result
    
    print *, "Enter two numbers:"
    read *, a, b
    result = a + b
    print *, "Sum:", result
end program calculator
"#);

let result = parser.parse(&source);
println!("Program parsed successfully.");

Subroutine Parsing

use oak_fortran::{Parser, FortranLanguage, SourceText};

let parser = Parser::new();
let source = SourceText::new(r#"
subroutine swap(a, b)
    implicit none
    real, intent(inout) :: a, b
    real :: temp
    
    temp = a
    a = b
    b = temp
end subroutine swap

program test
    implicit none
    real :: x = 1.0, y = 2.0
    
    print *, "Before swap: x =", x, "y =", y
    call swap(x, y)
    print *, "After swap: x =", x, "y =", y
end program test
"#);

let result = parser.parse(&source);
println!("Subroutine parsed successfully.");

Function Parsing

use oak_fortran::{Parser, FortranLanguage, SourceText};

let parser = Parser::new();
let source = SourceText::new(r#"
function factorial(n) result(fact)
    implicit none
    integer, intent(in) :: n
    integer :: fact
    
    if (n <= 0) then
        fact = 1
    else
        fact = n * factorial(n - 1)
    end if
end function factorial

program test
    implicit none
    integer :: n = 5
    
    print *, "Factorial of", n, "is", factorial(n)
end program test
"#);

let result = parser.parse(&source);
println!("Function parsed successfully.");

🔧 Advanced Features

Token-Level Parsing

use oak_fortran::{Parser, FortranLanguage, SourceText};

let parser = Parser::new();
let source = SourceText::new("x = 42.0");
let result = parser.parse(&source);
println!("Token parsing completed.");

Error Handling

use oak_fortran::{Parser, FortranLanguage, SourceText};

let parser = Parser::new();
let source = SourceText::new(r#"
program broken
    implicit none
    real :: x
    
    print *, "Hello, Fortran!"
    x = 5
    ! Missing end program statement
"#);

let result = parser.parse(&source);
if let Some(errors) = result.result.err() {
    println!("Parse errors found: {:?}", errors);
} else {
    println!("Parsed successfully.");
}

🏗️ AST Structure

The parser generates a comprehensive AST with the following main structures:

• Program: Root container for Fortran programs
• Subroutine: Subroutine definitions
• Function: Function definitions
• Module: Module definitions
• Statement: Various statement types including control flow
• Expression: Various expression types including operators

📊 Performance

• Streaming: Parse large Fortran files without loading entirely into memory
• Incremental: Re-parse only changed sections
• Memory Efficient: Smart AST node allocation
• Fast Recovery: Quick error recovery for better IDE integration

🔗 Integration

Oak Fortran integrates seamlessly with:

• Compilers: Front-end for Fortran compilers
• Static Analysis Tools: Code quality and security analysis
• IDE Support: Language server protocol compatibility
• Code Generation: Generating code from AST

📚 Examples

Check out the examples directory for comprehensive examples:

• Complete Fortran program parsing
• Subroutine and function analysis
• Code transformation
• Integration with development workflows

🤝 Contributing

Contributions are welcome!

Please feel free to submit pull requests at the project repository or open issues.