Add else if control flow.
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README.md
38
README.md
@ -190,6 +190,18 @@ fn main() {
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}
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```
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To return a `Dynamic` value, simply `Box` it and return it.
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```rust
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fn decide(yes_no: bool) -> Dynamic {
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if yes_no {
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Box::new(42_i64)
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} else {
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Box::new("hello world!".to_string()) // remember &str is not supported
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}
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}
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```
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# Working with generic functions
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Generic functions can be used in Rhai, but you'll need to register separate instances for each concrete type:
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@ -217,7 +229,7 @@ You can also see in this example how you can register multiple functions (or in
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# Override built-in functions
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Any similarly-named function defined in a script with the correct argument types overrides any built-in function.
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Any similarly-named function defined in a script overrides any built-in function.
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```rust
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// Override the built-in function 'to_int'
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@ -445,9 +457,10 @@ this() & that(); // both this() and that() are evaluated
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```rust
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if true {
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print("it's true!");
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}
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else {
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print("It's true!");
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} else if true {
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print("It's true again!");
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} else {
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print("It's false!");
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}
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```
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@ -456,11 +469,10 @@ else {
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```rust
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let x = 10;
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while x > 0 {
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print(x);
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if x == 5 {
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break;
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}
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if x == 5 { break; }
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x = x - 1;
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}
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```
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@ -499,18 +511,6 @@ fn add(x, y) {
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print(add(2, 3))
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```
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To return a `Dynamic` value, simply `Box` it and return it.
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```rust
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fn decide(yes_no: bool) -> Dynamic {
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if yes_no {
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Box::new(42_i64)
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} else {
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Box::new("hello world!".to_string()) // remember &str is not supported
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}
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}
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```
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## Arrays
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You can create arrays of values, and then access them with numeric indices.
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@ -818,18 +818,6 @@ impl Engine {
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last_result
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}
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Stmt::If(guard, body) => self
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.eval_expr(scope, guard)?
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.downcast::<bool>()
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.map_err(|_| EvalAltResult::ErrorIfGuard)
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.and_then(|guard_val| {
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if *guard_val {
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self.eval_stmt(scope, body)
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} else {
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Ok(Box::new(()))
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}
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}),
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Stmt::IfElse(guard, body, else_body) => self
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.eval_expr(scope, guard)?
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.downcast::<bool>()
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@ -837,8 +825,10 @@ impl Engine {
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.and_then(|guard_val| {
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if *guard_val {
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self.eval_stmt(scope, body)
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} else if else_body.is_some() {
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self.eval_stmt(scope, else_body.as_ref().unwrap())
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} else {
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self.eval_stmt(scope, else_body)
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Ok(Box::new(()))
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}
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}),
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@ -155,8 +155,7 @@ pub struct FnDef {
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#[derive(Debug, Clone)]
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pub enum Stmt {
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If(Box<Expr>, Box<Stmt>),
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IfElse(Box<Expr>, Box<Stmt>, Box<Stmt>),
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IfElse(Box<Expr>, Box<Stmt>, Option<Box<Stmt>>),
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While(Box<Expr>, Box<Stmt>),
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Loop(Box<Stmt>),
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For(String, Box<Expr>, Box<Stmt>),
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@ -1308,14 +1307,19 @@ fn parse_if<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, ParseEr
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match input.peek() {
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Some(&(Token::Else, _)) => {
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input.next();
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let else_body = parse_block(input)?;
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let else_body = match input.peek() {
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Some(&(Token::If, _)) => parse_if(input)?,
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_ => parse_block(input)?,
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};
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Ok(Stmt::IfElse(
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Box::new(guard),
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Box::new(body),
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Box::new(else_body),
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Some(Box::new(else_body)),
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))
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}
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_ => Ok(Stmt::If(Box::new(guard), Box::new(body))),
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_ => Ok(Stmt::IfElse(Box::new(guard), Box::new(body), None)),
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}
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}
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@ -7,4 +7,21 @@ fn test_if() {
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assert_eq!(engine.eval::<i64>("if true { 55 }"), Ok(55));
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assert_eq!(engine.eval::<i64>("if false { 55 } else { 44 }"), Ok(44));
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assert_eq!(engine.eval::<i64>("if true { 55 } else { 44 }"), Ok(55));
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assert_eq!(
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engine.eval::<i64>("if false { 55 } else if true { 33 } else { 44 }"),
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Ok(33)
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);
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assert_eq!(
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engine.eval::<i64>(
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r"
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if false { 55 }
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else if false { 33 }
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else if false { 66 }
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else if false { 77 }
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else if false { 88 }
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else { 44 }
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"
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),
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Ok(44)
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);
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}
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