tinyscript 0.6.1

Tiny, C-like scripting language.
Documentation 
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// Copyright © 2025 Stephan Kunz
//! [`AssignmentParselet`] handles all kinds of assignments.

use crate::{
	compilation::{
		CompilationError, Lexer, Parser,
		token::{Token, TokenKind},
	},
	execution::{Chunk, op_code::OpCode},
	scripting_value::ScriptingValue,
};

use super::PrefixParselet;

#[derive(Clone)]
pub struct AssignmentParselet;

impl PrefixParselet for AssignmentParselet {
	fn parse(
		&self,
		lexer: &mut Lexer,
		parser: &mut Parser,
		chunk: &mut Chunk,
		token: Token,
	) -> Result<(), CompilationError> {
		let next = parser.next();
		match next.kind {
			TokenKind::ColonEqual => {
				parser.advance(lexer)?;
				parser.expression(lexer, chunk)?;
				let name = chunk.add_constant(ScriptingValue::String(token.origin))?;
				parser.emit_bytes(OpCode::DefineExternal as u8, name, chunk);
			}
			TokenKind::PlusEqual => {
				let name = chunk.add_constant(ScriptingValue::String(token.origin))?;
				parser.emit_bytes(OpCode::GetExternal as u8, name, chunk);
				parser.advance(lexer)?;
				parser.expression(lexer, chunk)?;
				parser.emit_byte(OpCode::Add as u8, chunk);
				parser.emit_bytes(OpCode::SetExternal as u8, name, chunk);
			}
			TokenKind::MinusEqual => {
				let name = chunk.add_constant(ScriptingValue::String(token.origin))?;
				parser.emit_bytes(OpCode::GetExternal as u8, name, chunk);
				parser.advance(lexer)?;
				parser.expression(lexer, chunk)?;
				parser.emit_byte(OpCode::Subtract as u8, chunk);
				parser.emit_bytes(OpCode::SetExternal as u8, name, chunk);
			}
			TokenKind::StarEqual => {
				let name = chunk.add_constant(ScriptingValue::String(token.origin))?;
				parser.emit_bytes(OpCode::GetExternal as u8, name, chunk);
				parser.advance(lexer)?;
				parser.expression(lexer, chunk)?;
				parser.emit_byte(OpCode::Multiply as u8, chunk);
				parser.emit_bytes(OpCode::SetExternal as u8, name, chunk);
			}
			TokenKind::SlashEqual => {
				let name = chunk.add_constant(ScriptingValue::String(token.origin))?;
				parser.emit_bytes(OpCode::GetExternal as u8, name, chunk);
				parser.advance(lexer)?;
				parser.expression(lexer, chunk)?;
				parser.emit_byte(OpCode::Divide as u8, chunk);
				parser.emit_bytes(OpCode::SetExternal as u8, name, chunk);
			}
			TokenKind::Equal => {
				parser.advance(lexer)?;
				parser.expression(lexer, chunk)?;
				let name = chunk.add_constant(ScriptingValue::String(token.origin))?;
				parser.emit_bytes(OpCode::SetExternal as u8, name, chunk);
			}
			_ => {
				let name = chunk.add_constant(ScriptingValue::String(token.origin))?;
				parser.emit_bytes(OpCode::GetExternal as u8, name, chunk);
			}
		}
		Ok(())
	}
}

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

	// check, that the auto traits are available
	const fn is_normal<T: Sized + Send + Sync>() {}

	#[test]
	const fn normal_types() {
		is_normal::<&AssignmentParselet>();
		is_normal::<AssignmentParselet>();
	}
}