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//! # merge_whitespace
//!
//! This crate contains procedural macros for removing multiple consecutive whitespaces from a
//! given string literal, replacing them with a single space.
//!
//! ## Example
//!
//! ```
//! # use merge_whitespace::merge_whitespace;
//! const QUERY: &str = merge_whitespace!(r#"
//!                 query {
//!                   users (limit: 1) {
//!                     id
//!                     name
//!                     todos(order_by: {created_at: desc}, limit: 5) {
//!                       id
//!                       title
//!                     }
//!                   }
//!                 }
//!                 "#);
//!
//! assert_eq!(QUERY, "query { users (limit: 1) { id name todos(order_by: {created_at: desc}, limit: 5) { id title } } }");
//! ```

use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, LitStr};

/// This is a procedural macro that removes multiple consecutive whitespaces from a given string
/// literal and replaces them with a single space.
///
/// ## Example
///
/// ```
/// # use merge_whitespace::merge_whitespace;///
/// let output = merge_whitespace!("Hello     World!\r\n      How        are         you?");
/// assert_eq!(output, "Hello World! How are you?");
/// ```
///
/// # Return
///
/// The macro expands to the modified string literal.
#[proc_macro]
pub fn merge_whitespace(input: TokenStream) -> TokenStream {
    // Parse the input tokens into a syntax tree
    let input = parse_macro_input!(input as LitStr);

    // Get the string literal value
    let input_str = input.value();

    // Replace multiple whitespaces with a single space
    let output_str = input_str.split_whitespace().collect::<Vec<_>>().join(" ");

    // Generate the output tokens
    let output = quote! {
        #output_str
    };

    output.into()
}