rhai/tests/custom_syntax.rs

#![cfg(not(feature = "no_custom_syntax"))]

use rhai::{
    Dynamic, Engine, EvalAltResult, ImmutableString, LexError, ParseErrorType, Position, Scope, INT,
};

#[test]
fn test_custom_syntax() -> Result<(), Box<EvalAltResult>> {
    let mut engine = Engine::new();

    engine.run("while false {}")?;

    // Disable 'while' and make sure it still works with custom syntax
    engine.disable_symbol("while");
    assert!(matches!(
        engine.compile("while false {}").unwrap_err().err_type(),
        ParseErrorType::Reserved(err) if err == "while"
    ));
    assert!(matches!(
        engine.compile("let while = 0").unwrap_err().err_type(),
        ParseErrorType::Reserved(err) if err == "while"
    ));

    // Implement ternary operator
    engine.register_custom_syntax(
        ["iff", "$expr$", "?", "$expr$", ":", "$expr$"],
        false,
        |context, inputs| match context.eval_expression_tree(&inputs[0])?.as_bool() {
            Ok(true) => context.eval_expression_tree(&inputs[1]),
            Ok(false) => context.eval_expression_tree(&inputs[2]),
            Err(typ) => Err(Box::new(EvalAltResult::ErrorMismatchDataType(
                "bool".to_string(),
                typ.to_string(),
                inputs[0].position(),
            ))),
        },
    )?;

    assert_eq!(
        engine.eval::<INT>(
            "
                let x = 42;
                let y = iff x > 40 ? 0 : 123;
                y
            "
        )?,
        0
    );

    assert_eq!(
        engine.eval::<INT>(
            "
                let x = 42;
                let y = iff x == 0 ? 0 : 123;
                y
            "
        )?,
        123
    );

    // Custom syntax
    engine.register_custom_syntax(
        [
            "exec", "[", "$ident$", "$symbol$", "$int$", "]", "->", "$block$", "while", "$expr$",
        ],
        true,
        |context, inputs| {
            let var_name = inputs[0].get_string_value().unwrap();
            let op = inputs[1].get_literal_value::<ImmutableString>().unwrap();
            let max = inputs[2].get_literal_value::<INT>().unwrap();
            let stmt = &inputs[3];
            let condition = &inputs[4];

            context.scope_mut().push(var_name.to_string(), 0 as INT);

            let mut count: INT = 0;

            loop {
                let done = match op.as_str() {
                    "<" => count >= max,
                    "<=" => count > max,
                    ">" => count <= max,
                    ">=" => count < max,
                    "==" => count != max,
                    "!=" => count == max,
                    _ => return Err(format!("Unsupported operator: {op}").into()),
                };

                if done {
                    break;
                }

                // Do not rewind if the variable is upper-case
                let _: Dynamic = if var_name.to_uppercase() == var_name {
                    #[allow(deprecated)] // not deprecated but unstable
                    context.eval_expression_tree_raw(stmt, false)
                } else {
                    context.eval_expression_tree(stmt)
                }?;

                count += 1;

                context
                    .scope_mut()
                    .push(format!("{var_name}{count}"), count);

                let stop = !context
                    .eval_expression_tree(condition)?
                    .as_bool()
                    .map_err(|err| {
                        Box::new(EvalAltResult::ErrorMismatchDataType(
                            "bool".to_string(),
                            err.to_string(),
                            condition.position(),
                        ))
                    })?;

                if stop {
                    break;
                }
            }

            Ok(count.into())
        },
    )?;

    assert!(matches!(
        *engine
            .run("let foo = (exec [x<<15] -> { x += 2 } while x < 42) * 10;")
            .unwrap_err(),
        EvalAltResult::ErrorRuntime(..)
    ));

    assert_eq!(
        engine.eval::<INT>(
            "
                let x = 0;
                let foo = (exec [x<15] -> { x += 2 } while x < 42) * 10;
                foo
            "
        )?,
        150
    );
    assert_eq!(
        engine.eval::<INT>(
            "
                let x = 0;
                exec [x<100] -> { x += 1 } while x < 42;
                x
            "
        )?,
        42
    );
    assert_eq!(
        engine.eval::<INT>(
            "
                exec [x<100] -> { x += 1 } while x < 42;
                x
            "
        )?,
        42
    );
    assert_eq!(
        engine.eval::<INT>(
            "
                let foo = 123;
                exec [x<15] -> { x += 1 } while x < 42;
                foo + x + x1 + x2 + x3
            "
        )?,
        144
    );
    assert_eq!(
        engine.eval::<INT>(
            "
                let foo = 123;
                exec [x<15] -> { let foo = x; x += 1; } while x < 42;
                foo
            "
        )?,
        123
    );
    assert_eq!(
        engine.eval::<INT>(
            "
                let foo = 123;
                exec [ABC<15] -> { let foo = ABC; ABC += 1; } while ABC < 42;
                foo
            "
        )?,
        14
    );

    // The first symbol must be an identifier
    assert_eq!(
        *engine
            .register_custom_syntax(["!"], false, |_, _| Ok(Dynamic::UNIT))
            .unwrap_err()
            .err_type(),
        ParseErrorType::BadInput(LexError::ImproperSymbol(
            "!".to_string(),
            "Improper symbol for custom syntax at position #1: '!'".to_string()
        ))
    );

    // Check self-termination
    engine
        .register_custom_syntax(["test1", "$block$"], true, |_, _| Ok(Dynamic::UNIT))?
        .register_custom_syntax(["test2", "}"], true, |_, _| Ok(Dynamic::UNIT))?
        .register_custom_syntax(["test3", ";"], true, |_, _| Ok(Dynamic::UNIT))?;

    assert_eq!(engine.eval::<INT>("test1 { x = y + z; } 42")?, 42);
    assert_eq!(engine.eval::<INT>("test2 } 42")?, 42);
    assert_eq!(engine.eval::<INT>("test3; 42")?, 42);

    // Register the custom syntax: var x = ???
    engine.register_custom_syntax(
        ["var", "$ident$", "=", "$expr$"],
        true,
        |context, inputs| {
            let var_name = inputs[0].get_string_value().unwrap();
            let expr = &inputs[1];

            // Evaluate the expression
            let value = context.eval_expression_tree(expr)?;

            if !context.scope().is_constant(var_name).unwrap_or(false) {
                context.scope_mut().set_value(var_name.to_string(), value);
                Ok(Dynamic::UNIT)
            } else {
                Err(format!("variable {var_name} is constant").into())
            }
        },
    )?;

    let mut scope = Scope::new();

    assert_eq!(
        engine.eval_with_scope::<INT>(&mut scope, "var foo = 42; foo")?,
        42
    );
    assert_eq!(scope.get_value::<INT>("foo"), Some(42));
    assert_eq!(scope.len(), 1);
    assert_eq!(
        engine.eval_with_scope::<INT>(&mut scope, "var foo = 123; foo")?,
        123
    );
    assert_eq!(scope.get_value::<INT>("foo"), Some(123));
    assert_eq!(scope.len(), 1);

    Ok(())
}

#[test]
fn test_custom_syntax_scope() -> Result<(), Box<EvalAltResult>> {
    let mut engine = Engine::new();

    engine.register_custom_syntax(
        [
            "with", "offset", "(", "$expr$", ",", "$expr$", ")", "$block$",
        ],
        true,
        |context, inputs| {
            let x = context
                .eval_expression_tree(&inputs[0])?
                .as_int()
                .map_err(|typ| {
                    Box::new(EvalAltResult::ErrorMismatchDataType(
                        "integer".to_string(),
                        typ.to_string(),
                        inputs[0].position(),
                    ))
                })?;

            let y = context
                .eval_expression_tree(&inputs[1])?
                .as_int()
                .map_err(|typ| {
                    Box::new(EvalAltResult::ErrorMismatchDataType(
                        "integer".to_string(),
                        typ.to_string(),
                        inputs[1].position(),
                    ))
                })?;

            let orig_len = context.scope().len();

            context.scope_mut().push_constant("x", x);
            context.scope_mut().push_constant("y", y);

            let result = context.eval_expression_tree(&inputs[2]);

            context.scope_mut().rewind(orig_len);

            result
        },
    )?;

    assert_eq!(
        engine.eval::<INT>(
            "
                let y = 1;
                let x = 0;
                with offset(44, 2) { x - y }
            "
        )?,
        42
    );

    Ok(())
}

#[test]
fn test_custom_syntax_matrix() -> Result<(), Box<EvalAltResult>> {
    let mut engine = Engine::new();

    engine.disable_symbol("|");

    engine.register_custom_syntax(
        [
            "@", //
            "|", "$expr$", "$expr$", "$expr$", "|", //
            "|", "$expr$", "$expr$", "$expr$", "|", //
            "|", "$expr$", "$expr$", "$expr$", "|",
        ],
        false,
        |context, inputs| {
            let mut values = [[0; 3]; 3];

            for y in 0..3 {
                for x in 0..3 {
                    let offset = y * 3 + x;

                    match context.eval_expression_tree(&inputs[offset])?.as_int() {
                        Ok(v) => values[y][x] = v,
                        Err(typ) => {
                            return Err(Box::new(EvalAltResult::ErrorMismatchDataType(
                                "integer".to_string(),
                                typ.to_string(),
                                inputs[offset].position(),
                            )))
                        }
                    }
                }
            }

            Ok(Dynamic::from(values))
        },
    )?;

    let r = engine.eval::<[[INT; 3]; 3]>(
        "
            let a = 42;
            let b = 123;
            let c = 1;
            let d = 99;

            @|  a   b   0  |
             | -b   a   0  |
             |  0   0  c*d |
        ",
    )?;

    assert_eq!(r, [[42, 123, 0], [-123, 42, 0], [0, 0, 99]]);

    Ok(())
}

#[test]
fn test_custom_syntax_raw() -> Result<(), Box<EvalAltResult>> {
    let mut engine = Engine::new();

    engine.register_custom_syntax_with_state_raw(
        "hello",
        |stream, look_ahead, state| match stream.len() {
            0 => unreachable!(),
            1 if look_ahead == "\"world\"" => {
                *state = Dynamic::TRUE;
                Ok(Some("$string$".into()))
            }
            1 => {
                *state = Dynamic::FALSE;
                Ok(Some("$ident$".into()))
            }
            2 => {
                match stream[1].as_str() {
                    "world" if state.as_bool().unwrap_or(false) => Ok(Some("$$world".into())),
                    "world" => Ok(Some("$$hello".into())),
                    "kitty" => {
                        *state = (42 as INT).into();
                        Ok(None)
                    }
                    s => Err(LexError::ImproperSymbol(s.to_string(), String::new())
                        .into_err(Position::NONE)),
                }
            }
            _ => unreachable!(),
        },
        true,
        |context, inputs, state| {
            context.scope_mut().push("foo", 999 as INT);

            Ok(match inputs[0].get_string_value().unwrap() {
                "world" => match inputs.last().unwrap().get_string_value().unwrap_or("") {
                    "$$hello" => 0 as INT,
                    "$$world" => 123456 as INT,
                    _ => 123 as INT,
                },
                "kitty" if inputs.len() > 1 => 999 as INT,
                "kitty" => state.as_int().unwrap(),
                _ => unreachable!(),
            }
            .into())
        },
    );

    assert_eq!(engine.eval::<INT>(r#"hello "world""#)?, 123456);
    assert_eq!(engine.eval::<INT>("hello world")?, 0);
    assert_eq!(engine.eval::<INT>("hello kitty")?, 42);
    assert_eq!(
        engine.eval::<INT>("let foo = 0; (hello kitty) + foo")?,
        1041
    );
    assert_eq!(engine.eval::<INT>("(hello kitty) + foo")?, 1041);
    assert_eq!(
        *engine.compile("hello hey").unwrap_err().err_type(),
        ParseErrorType::BadInput(LexError::ImproperSymbol("hey".to_string(), String::new()))
    );

    Ok(())
}

#[test]
fn test_custom_syntax_raw2() -> Result<(), Box<EvalAltResult>> {
    let mut engine = Engine::new();

    engine.register_custom_syntax_with_state_raw(
        "#",
        |symbols, lookahead, _| match symbols.len() {
            1 if lookahead == "-" => Ok(Some("$symbol$".into())),
            1 => Ok(Some("$int$".into())),
            2 if symbols[1] == "-" => Ok(Some("$int$".into())),
            2 => Ok(None),
            3 => Ok(None),
            _ => unreachable!(),
        },
        false,
        move |_, inputs, _| {
            let id = if inputs.len() == 2 {
                -inputs[1].get_literal_value::<INT>().unwrap()
            } else {
                inputs[0].get_literal_value::<INT>().unwrap()
            };
            Ok(id.into())
        },
    );

    assert_eq!(engine.eval::<INT>("#-1")?, -1);
    assert_eq!(engine.eval::<INT>("let x = 41; x + #1")?, 42);
    #[cfg(not(feature = "no_object"))]
    assert_eq!(engine.eval::<INT>("#-42.abs()")?, 42);
    assert_eq!(engine.eval::<INT>("#42/2")?, 21);
    assert_eq!(engine.eval::<INT>("sign(#1)")?, 1);

    Ok(())
}