Print arrays and maps with to_debug.

RELEASES.md

@@ -13,6 +13,8 @@ Enhancements
 ------------
 
 * Property getters/setters and indexers defined in a plugin module are by default `#[rhai_fn(global)]`.
+* `to_debug` is a new standard function for converting a value into debug format.
+* Arrays and object maps now print values using `to_debug` (if available).
 
 
 Version 0.19.6

doc/src/language/values-and-types.md

@@ -38,3 +38,5 @@ is an alias to `Rc<String>` or `Arc<String>` (depending on the [`sync`] feature)
 Any modification done to a Rhai string will cause the string to be cloned and the modifications made to the copy.
 
 The `to_string` function converts a standard type into a [string] for display purposes.
+
+The `to_debug` function converts a standard type into a [string] in debug format.

doc/src/patterns/enums.md

@@ -61,7 +61,7 @@ mod MyEnumModule {
         }
     }
     // Printing
-    #[rhai(global, name = "to_string", name = "print", name = "debug")]
+    #[rhai(global, name = "to_string", name = "print", name = "to_debug", name = "debug")]
     pub fn to_string(a: &mut MyEnum) -> String {
         format!("{:?}", a))
     }

doc/src/rust/print-custom.md

@@ -11,6 +11,7 @@ is `T: Display + Debug`):
 | ----------- | ---------------------------------------------- | ---------------------------- | -------------------------------------------------------------------- |
 | `to_string` | <code>\|x: &mut T\| -> String</code>           | `x.to_string()`              | converts the custom type into a [string]                             |
 | `print`     | <code>\|x: &mut T\| -> String</code>           | `x.to_string()`              | converts the custom type into a [string] for the [`print`] statement |
+| `to_debug`  | <code>\|x: &mut T\| -> String</code>           | `format!("{:?}", x)`         | converts the custom type into a [string] in debug format             |
 | `debug`     | <code>\|x: &mut T\| -> String</code>           | `format!("{:?}", x)`         | converts the custom type into a [string] for the [`debug`] statement |
 | `+`         | <code>\|s: &str, x: T\| -> String</code>       | `format!("{}{}", s, x)`      | concatenates the custom type with another [string]                   |
 | `+`         | <code>\|x: &mut T, s: &str\| -> String</code>  | `x.to_string().push_str(s);` | concatenates another [string] with the custom type                   |

src/fn_native.rs

@@ -134,7 +134,7 @@ impl<'e, 'a, 'm, 'pm> NativeCallContext<'e, 'a, 'm, 'pm> {
     /// If `is_method` is [`true`], the first argument is assumed to be passed
     /// by reference and is not consumed.
     pub fn call_fn_dynamic_raw(
-        &mut self,
+        &self,
         fn_name: &str,
         is_method: bool,
         public_only: bool,
@@ -262,7 +262,7 @@ impl FnPtr {
     /// clone them _before_ calling this function.
     pub fn call_dynamic(
         &self,
-        mut ctx: NativeCallContext,
+        ctx: NativeCallContext,
         this_ptr: Option<&mut Dynamic>,
         mut arg_values: impl AsMut<[Dynamic]>,
     ) -> Result<Dynamic, Box<EvalAltResult>> {

src/packages/array_basic.rs

@@ -650,7 +650,7 @@ mod array_functions {
     }
     #[rhai_fn(name = "==", return_raw)]
     pub fn equals(
-        mut ctx: NativeCallContext,
+        ctx: NativeCallContext,
         arr1: &mut Array,
         mut arr2: Array,
     ) -> Result<Dynamic, Box<EvalAltResult>> {

src/packages/map_basic.rs

@@ -45,7 +45,7 @@ mod map_functions {
     }
     #[rhai_fn(name = "==", return_raw)]
     pub fn equals(
-        mut ctx: NativeCallContext,
+        ctx: NativeCallContext,
         map1: &mut Map,
         mut map2: Map,
     ) -> Result<Dynamic, Box<EvalAltResult>> {

src/packages/string_basic.rs

@@ -15,6 +15,9 @@ use crate::Array;
 #[cfg(not(feature = "no_object"))]
 use crate::Map;
 
+const FUNC_TO_STRING: &'static str = "to_string";
+const FUNC_TO_DEBUG: &'static str = "to_debug";
+
 type Unit = ();
 
 macro_rules! gen_functions {
@@ -32,13 +35,14 @@ macro_rules! gen_functions {
 
 macro_rules! reg_print_functions {
     ($mod_name:ident += $root:ident ; $($arg_type:ident),+) => { $(
-        set_exported_fn!($mod_name, "to_string", $root::$arg_type::to_string_func);
+        set_exported_fn!($mod_name, FUNC_TO_STRING, $root::$arg_type::to_string_func);
         set_exported_fn!($mod_name, KEYWORD_PRINT, $root::$arg_type::to_string_func);
     )* }
 }
 
 macro_rules! reg_debug_functions {
     ($mod_name:ident += $root:ident ; $($arg_type:ident),+) => { $(
+        set_exported_fn!($mod_name, FUNC_TO_DEBUG, $root::$arg_type::to_string_func);
         set_exported_fn!($mod_name, KEYWORD_DEBUG, $root::$arg_type::to_string_func);
     )* }
 }
@@ -67,12 +71,6 @@ def_package!(crate:BasicStringPackage:"Basic string utilities, including printin
         reg_print_functions!(lib += print_float; f32, f64);
         reg_debug_functions!(lib += debug_float; f32, f64);
     }
-
-    #[cfg(not(feature = "no_index"))]
-    {
-        reg_print_functions!(lib += print_array; Array);
-        reg_debug_functions!(lib += print_array; Array);
-    }
 });
 
 fn to_string<T: Display>(x: &mut T) -> ImmutableString {
@@ -109,10 +107,18 @@ gen_functions!(print_float => to_string(f32, f64));
 #[cfg(not(feature = "no_float"))]
 gen_functions!(debug_float => to_debug(f32, f64));
 
-#[cfg(not(feature = "no_index"))]
-gen_functions!(print_array => to_debug(Array));
-
 // Register print and debug
+
+#[cfg(not(feature = "no_index"))]
+#[inline(always)]
+fn print_with_func(fn_name: &str, ctx: &NativeCallContext, value: &mut Dynamic) -> ImmutableString {
+    match ctx.call_fn_dynamic_raw(fn_name, true, false, &mut [value], None) {
+        Ok(result) if result.is::<ImmutableString>() => result.take_immutable_string().unwrap(),
+        Ok(result) => ctx.engine().map_type_name(result.type_name()).into(),
+        Err(_) => ctx.engine().map_type_name(value.type_name()).into(),
+    }
+}
+
 #[export_module]
 mod print_debug_functions {
     #[rhai_fn(name = "print", name = "debug")]
@@ -132,13 +138,50 @@ mod print_debug_functions {
         to_string(f)
     }
 
+    #[cfg(not(feature = "no_index"))]
+    pub mod array_functions {
+        use super::*;
+
+        #[rhai_fn(name = "print", name = "to_string", name = "to_debug", name = "debug")]
+        pub fn format_array(ctx: NativeCallContext, arr: &mut Array) -> ImmutableString {
+            let mut result = String::with_capacity(16);
+            result.push_str("[");
+
+            let len = arr.len();
+
+            arr.iter_mut().enumerate().for_each(|(i, x)| {
+                result.push_str(&print_with_func(FUNC_TO_DEBUG, &ctx, x));
+                if i < len - 1 {
+                    result.push_str(", ");
+                }
+            });
+
+            result.push_str("]");
+            result.into()
+        }
+    }
     #[cfg(not(feature = "no_object"))]
     pub mod map_functions {
         use super::*;
 
-        #[rhai_fn(name = "print", name = "debug", name = "to_string")]
+        #[rhai_fn(name = "print", name = "to_string", name = "to_debug", name = "debug")]
-        pub fn format_map(x: &mut Map) -> ImmutableString {
+        pub fn format_map(ctx: NativeCallContext, map: &mut Map) -> ImmutableString {
-            format!("#{:?}", x).into()
+            let mut result = String::with_capacity(16);
+            result.push_str("#{");
+
+            let len = map.len();
+
+            map.iter_mut().enumerate().for_each(|(i, (k, v))| {
+                result.push_str(k);
+                result.push_str(": ");
+                result.push_str(&print_with_func(FUNC_TO_DEBUG, &ctx, v));
+                if i < len - 1 {
+                    result.push_str(", ");
+                }
+            });
+
+            result.push_str("}");
+            result.into()
         }
     }
 }

tests/print.rs

@@ -1,4 +1,4 @@
-use rhai::{Engine, EvalAltResult};
+use rhai::{Engine, EvalAltResult, RegisterFn, INT};
 use std::sync::{Arc, RwLock};
 
 #[test]
@@ -30,3 +30,49 @@ fn test_print() -> Result<(), Box<EvalAltResult>> {
 
     Ok(())
 }
+
+#[derive(Debug, Clone, Eq, PartialEq, Hash, Default)]
+struct MyStruct {
+    field: INT,
+}
+
+impl std::fmt::Display for MyStruct {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "hello: {}", self.field)
+    }
+}
+
+#[test]
+fn test_print_custom_type() -> Result<(), Box<EvalAltResult>> {
+    let mut engine = Engine::new();
+
+    engine
+        .register_type_with_name::<MyStruct>("MyStruct")
+        .register_fn("to_debug", |x: &mut MyStruct| x.to_string())
+        .register_fn("debug", |x: &mut MyStruct| x.to_string())
+        .register_fn("new_ts", || MyStruct { field: 42 });
+
+    engine.consume("let x = new_ts(); debug(x);")?;
+
+    #[cfg(not(feature = "no_index"))]
+    assert_eq!(
+        engine.eval::<String>(
+            r#"
+                let x = [ 123, true, (), "world", new_ts() ];
+                x.to_string()
+            "#
+        )?,
+        r#"[123, true, (), "world", hello: 42]"#
+    );
+
+    #[cfg(not(feature = "no_object"))]
+    assert!(engine
+        .eval::<String>(
+            r#"
+                let x = #{ a:123, b:true, c:(), d:"world", e:new_ts() };
+                x.to_string()
+            "#
+        )?
+        .contains("e: hello: 42"));
+    Ok(())
+}