Function parse_function_decl 

pub fn parse_function_decl(input: &str) -> ParseResult<Pairs<'_, Rule>>

Parses a single function declaration.

Use this function when you need to parse an individual function definition in isolation, without requiring a complete program context. This is useful for testing, code generation, incremental parsing, or working with code fragments.

Carbon Function Syntax

A function declaration in Carbon has the following structure:

fn function_name(param1: Type1, param2: Type2) -> ReturnType {
    // function body statements
    return expression;
}

Components:

• fn keyword to start the declaration
• Function name (identifier)
• Parameter list in parentheses (may be empty)
• Optional return type preceded by ->
• Function body in braces

Arguments

• input - A string slice containing exactly one function declaration

Returns

Returns a ParseResult containing the parsed function declaration tree.

Grammar Rule

This function uses the function_decl grammar rule from carbon.pest.

Examples

Function Without Parameters

use carbon_parser::parse_function_decl;

let code = "fn test() -> i32 { return 42; }";
let result = parse_function_decl(code);
assert!(result.is_ok());

Function With Single Parameter

use carbon_parser::parse_function_decl;

let code = "fn square(x: i32) -> i32 { return x; }";
let result = parse_function_decl(code);
assert!(result.is_ok());

Function With Multiple Parameters

use carbon_parser::parse_function_decl;

let code = "fn add(x: i32, y: i32, z: i32) -> i32 { return x; }";
let result = parse_function_decl(code);
assert!(result.is_ok());

Function Without Return Type

use carbon_parser::parse_function_decl;

let code = "fn print_hello() { return 0; }";
let result = parse_function_decl(code);
assert!(result.is_ok());

Function With Mixed Parameter Types

use carbon_parser::parse_function_decl;

let code = "fn process(name: String, age: i32, active: bool) -> bool { return active; }";
let result = parse_function_decl(code);
assert!(result.is_ok());