FIXED - method calls inside dot chain.

RELEASES.md

@@ -11,6 +11,11 @@ This version adds:
 * Ability to define custom operators (which must be valid identifiers).
 * Low-level API to register functions.
 
+Bug fixes
+---------
+
+* Fixed method calls in the middle of a dot chain.
+
 Breaking changes
 ----------------
 

doc/src/SUMMARY.md

@@ -105,9 +105,11 @@ The Rhai Scripting Language
       5. [Volatility Considerations](engine/optimize/volatility.md)
       6. [Subtle Semantic Changes](engine/optimize/semantics.md)
    4. [Low-Level API](rust/register-raw.md)
-   5. [Disable Keywords and/or Operators](engine/disable.md)
+   5. [Use as DSL](engine/dsl.md)
-   6. [Custom Operators](engine/custom-op.md)
+      1. [Disable Keywords and/or Operators](engine/disable.md)
-   7. [Eval Statement](language/eval.md)
+      2. [Custom Operators](engine/custom-op.md)
+      3. [Custom Syntax](engine/custom-syntax.md)
+   6. [Eval Statement](language/eval.md)
 9. [Appendix](appendix/index.md)
    1. [Keywords](appendix/keywords.md)
    2. [Operators and Symbols](appendix/operators.md)

doc/src/about/features.md

@@ -67,4 +67,4 @@ Flexible
 
 * Surgically [disable keywords and operators] to restrict the language.
 
-* [Custom operators].
+* Use as a [DSL] by [disabling keywords/operators][disable keywords and operators], [custom operators] and defining [custom syntax].

doc/src/appendix/operators.md

@@ -41,6 +41,7 @@ Symbols
 | ------------ | ------------------------ |
 | `:`          | Property value separator |
 | `::`         | Module path separator    |
+| `#`          | _Reserved_               |
 | `=>`         | _Reserved_               |
 | `->`         | _Reserved_               |
 | `<-`         | _Reserved_               |

doc/src/engine/custom-syntax.md

@@ -0,0 +1,5 @@
+Custom Syntax
+=============
+
+{{#include ../links.md}}
+

doc/src/engine/dsl.md

@@ -0,0 +1,80 @@
+Use Rhai as a Domain-Specific Language (DSL)
+===========================================
+
+{{#include ../links.md}}
+
+Rhai can be successfully used as a domain-specific language (DSL).
+
+
+Expressions Only
+----------------
+
+In many DSL scenarios, only evaluation of expressions is needed.
+
+The `Engine::eval_expression_XXX`[`eval_expression`] API can be used to restrict
+a script to expressions only.
+
+
+Disable Keywords and/or Operators
+--------------------------------
+
+In some DSL scenarios, it is necessary to further restrict the language to exclude certain
+language features that are not necessary or dangerous to the application.
+
+For example, a DSL may disable the `while` loop altogether while keeping all other statement
+types intact.
+
+It is possible, in Rhai, to surgically [disable keywords and operators].
+
+
+Custom Operators
+----------------
+
+On the other hand, some DSL scenarios require special operators that make sense only for
+that specific environment.  In such cases, it is possible to define [custom operators] in Rhai.
+
+For example:
+
+```rust
+let animal = "rabbit";
+let food = "carrot";
+
+animal eats food            // custom operator - 'eats'
+
+eats(animal, food)          // <- the above really de-sugars to this
+```
+
+Although a [custom operator] always de-sugars to a simple function call,
+nevertheless it makes the DSL syntax much simpler and expressive.
+
+
+Custom Syntax
+-------------
+
+For advanced DSL scenarios, it is possible to define entire expression [_syntax_][custom syntax] -
+essentially custom statement types.
+
+The [`internals`] feature is needed to be able to define [custom syntax] in Rhai.
+
+For example:
+
+```rust
+let table = [..., ..., ..., ...];
+
+// Syntax = "select" $ident$ $ident$ "from" $expr$ "->" $ident$ ":" $expr$
+let total = select sum price from table -> row : row.weight > 50;
+```
+
+After registering this custom syntax with Rhai, it can be used anywhere inside a script as
+a normal expression.
+
+For its evaluation, the callback function will receive the following list of parameters:
+
+`exprs[0] = "sum"` - math operator  
+`exprs[1] = "price"` - field name  
+`exprs[2] = Expr(table)` - data source  
+`exprs[3] = "row"` - loop variable name  
+`exprs[4] = Expr(row.wright > 50)` - expression  
+
+The other identified, such as `"select"`, `"from"`, as as as symbols `->` and `:` are
+parsed in the order defined within the custom syntax.

doc/src/links.md

@@ -89,6 +89,7 @@
 [`eval`]: {{rootUrl}}/language/eval.md
 
 [OOP]: {{rootUrl}}/language/oop.md
+[DSL]: {{rootUrl}}/engine/dsl.md
 
 [maximum statement depth]: {{rootUrl}}/safety/max-stmt-depth.md
 [maximum call stack depth]: {{rootUrl}}/safety/max-call-stack.md
@@ -107,3 +108,4 @@
 [disable keywords and operators]: {{rootUrl}}/engine/disable.md
 [custom operator]: {{rootUrl}}/engine/custom-op.md
 [custom operators]: {{rootUrl}}/engine/custom-op.md
+[custom syntax]: {{rootUrl}}/engine/custom-syntax.md

doc/src/start/features.md

@@ -25,7 +25,7 @@ more control over what a script can (or cannot) do.
 | `no_module`   | Disable loading external [modules].                                                                                                                                                                        |
 | `no_std`      | Build for `no-std`. Notice that additional dependencies will be pulled in to replace `std` features.                                                                                                       |
 | `serde`       | Enable serialization/deserialization via [`serde`]. Notice that the [`serde`](https://crates.io/crates/serde) crate will be pulled in together with its dependencies.                                      |
-| `internals`   | Expose internal data structures (e.g. [`AST`] nodes). Beware that Rhai internals are volatile and may change from version to version.                                                                      |
+| `internals`   | Expose internal data structures (e.g. [`AST`] nodes) and enable defining [custom syntax]. Beware that Rhai internals are volatile and may change from version to version.                                  |
 
 
 Example

src/engine.rs

@@ -1012,6 +1012,81 @@ impl Engine {
         return Ok(result);
     }
 
+    /// Call a dot method.
+    fn call_method(
+        &self,
+        state: &mut State,
+        lib: &Module,
+        target: &mut Target,
+        expr: &Expr,
+        mut idx_val: Dynamic,
+        level: usize,
+    ) -> Result<(Dynamic, bool), Box<EvalAltResult>> {
+        let ((name, native, pos), _, hash, _, def_val) = match expr {
+            Expr::FnCall(x) => x.as_ref(),
+            _ => unreachable!(),
+        };
+
+        let is_ref = target.is_ref();
+        let is_value = target.is_value();
+        let def_val = def_val.as_ref();
+
+        // Get a reference to the mutation target Dynamic
+        let obj = target.as_mut();
+        let idx = idx_val.downcast_mut::<StaticVec<Dynamic>>().unwrap();
+        let mut fn_name = name.as_ref();
+
+        // Check if it is a FnPtr call
+        let (result, updated) = if fn_name == KEYWORD_FN_PTR_CALL && obj.is::<FnPtr>() {
+            // Redirect function name
+            fn_name = obj.as_str().unwrap();
+            // Recalculate hash
+            let hash = calc_fn_hash(empty(), fn_name, idx.len(), empty());
+            // Arguments are passed as-is
+            let mut arg_values = idx.iter_mut().collect::<StaticVec<_>>();
+            let args = arg_values.as_mut();
+
+            // Map it to name(args) in function-call style
+            self.exec_fn_call(
+                state, lib, fn_name, *native, hash, args, false, false, def_val, level,
+            )
+        } else {
+            let redirected: Option<ImmutableString>;
+            let mut hash = *hash;
+
+            // Check if it is a map method call in OOP style
+            if let Some(map) = obj.downcast_ref::<Map>() {
+                if let Some(val) = map.get(fn_name) {
+                    if let Some(f) = val.downcast_ref::<FnPtr>() {
+                        // Remap the function name
+                        redirected = Some(f.get_fn_name().clone());
+                        fn_name = redirected.as_ref().unwrap();
+
+                        // Recalculate the hash based on the new function name
+                        hash = calc_fn_hash(empty(), fn_name, idx.len(), empty());
+                    }
+                }
+            };
+
+            // Attached object pointer in front of the arguments
+            let mut arg_values = once(obj).chain(idx.iter_mut()).collect::<StaticVec<_>>();
+            let args = arg_values.as_mut();
+
+            self.exec_fn_call(
+                state, lib, fn_name, *native, hash, args, is_ref, true, def_val, level,
+            )
+        }
+        .map_err(|err| err.new_position(*pos))?;
+
+        // Feed the changed temp value back
+        if updated && !is_ref && !is_value {
+            let new_val = target.as_mut().clone();
+            target.set_value(new_val)?;
+        }
+
+        Ok((result, updated))
+    }
+
     /// Chain-evaluate a dot/index chain.
     /// Position in `EvalAltResult` is None and must be set afterwards.
     fn eval_dot_index_chain_helper(
@@ -1031,7 +1106,6 @@ impl Engine {
         }
 
         let is_ref = target.is_ref();
-        let is_value = target.is_value();
 
         let next_chain = match rhs {
             Expr::Index(_) => ChainType::Index,
@@ -1040,7 +1114,7 @@ impl Engine {
         };
 
         // Pop the last index value
-        let mut idx_val = idx_values.pop();
+        let idx_val = idx_values.pop();
 
         match chain_type {
             #[cfg(not(feature = "no_index"))]
@@ -1124,69 +1198,7 @@ impl Engine {
                 match rhs {
                     // xxx.fn_name(arg_expr_list)
                     Expr::FnCall(x) if x.1.is_none() => {
-                        let ((name, native, pos), _, hash, _, def_val) = x.as_ref();
+                        self.call_method(state, lib, target, rhs, idx_val, level)
-                        let def_val = def_val.as_ref();
-
-                        // Get a reference to the mutation target Dynamic
-                        let (result, updated) = {
-                            let obj = target.as_mut();
-                            let idx = idx_val.downcast_mut::<StaticVec<Dynamic>>().unwrap();
-                            let mut fn_name = name.as_ref();
-
-                            // Check if it is a FnPtr call
-                            if fn_name == KEYWORD_FN_PTR_CALL && obj.is::<FnPtr>() {
-                                // Redirect function name
-                                fn_name = obj.as_str().unwrap();
-                                // Recalculate hash
-                                let hash = calc_fn_hash(empty(), fn_name, idx.len(), empty());
-                                // Arguments are passed as-is
-                                let mut arg_values = idx.iter_mut().collect::<StaticVec<_>>();
-                                let args = arg_values.as_mut();
-
-                                // Map it to name(args) in function-call style
-                                self.exec_fn_call(
-                                    state, lib, fn_name, *native, hash, args, false, false,
-                                    def_val, level,
-                                )
-                            } else {
-                                let redirected: Option<ImmutableString>;
-                                let mut hash = *hash;
-
-                                // Check if it is a map method call in OOP style
-                                if let Some(map) = obj.downcast_ref::<Map>() {
-                                    if let Some(val) = map.get(fn_name) {
-                                        if let Some(f) = val.downcast_ref::<FnPtr>() {
-                                            // Remap the function name
-                                            redirected = Some(f.get_fn_name().clone());
-                                            fn_name = redirected.as_ref().unwrap();
-
-                                            // Recalculate the hash based on the new function name
-                                            hash =
-                                                calc_fn_hash(empty(), fn_name, idx.len(), empty());
-                                        }
-                                    }
-                                };
-
-                                // Attached object pointer in front of the arguments
-                                let mut arg_values =
-                                    once(obj).chain(idx.iter_mut()).collect::<StaticVec<_>>();
-                                let args = arg_values.as_mut();
-
-                                self.exec_fn_call(
-                                    state, lib, fn_name, *native, hash, args, is_ref, true,
-                                    def_val, level,
-                                )
-                            }
-                            .map_err(|err| err.new_position(*pos))?
-                        };
-
-                        // Feed the changed temp value back
-                        if updated && !is_ref && !is_value {
-                            let new_val = target.as_mut().clone();
-                            target.set_value(new_val)?;
-                        }
-
-                        Ok((result, updated))
                     }
                     // xxx.module::fn_name(...) - syntax error
                     Expr::FnCall(_) => unreachable!(),
@@ -1230,16 +1242,26 @@ impl Engine {
                         .map(|(v, _)| (v, false))
                         .map_err(|err| err.new_position(*pos))
                     }
-                    // {xxx:map}.prop[expr] | {xxx:map}.prop.expr
+                    // {xxx:map}.sub_lhs[expr] | {xxx:map}.sub_lhs.expr
                     Expr::Index(x) | Expr::Dot(x) if target.is::<Map>() => {
-                        let (prop, expr, pos) = x.as_ref();
+                        let (sub_lhs, expr, pos) = x.as_ref();
 
-                        let mut val = if let Expr::Property(p) = prop {
+                        let mut val = match sub_lhs {
-                            let ((prop, _, _), _) = p.as_ref();
+                            Expr::Property(p) => {
-                            let index = prop.clone().into();
+                                let ((prop, _, _), _) = p.as_ref();
-                            self.get_indexed_mut(state, lib, target, index, *pos, false, level)?
+                                let index = prop.clone().into();
-                        } else {
+                                self.get_indexed_mut(state, lib, target, index, *pos, false, level)?
-                            unreachable!();
+                            }
+                            // {xxx:map}.fn_name(arg_expr_list)[expr] | {xxx:map}.fn_name(arg_expr_list).expr
+                            Expr::FnCall(x) if x.1.is_none() => {
+                                let (val, _) =
+                                    self.call_method(state, lib, target, sub_lhs, idx_val, level)?;
+                                val.into()
+                            }
+                            // {xxx:map}.module::fn_name(...) - syntax error
+                            Expr::FnCall(_) => unreachable!(),
+                            // Others - syntax error
+                            _ => unreachable!(),
                         };
 
                         self.eval_dot_index_chain_helper(
@@ -1248,49 +1270,72 @@ impl Engine {
                         )
                         .map_err(|err| err.new_position(*pos))
                     }
-                    // xxx.prop[expr] | xxx.prop.expr
+                    // xxx.sub_lhs[expr] | xxx.sub_lhs.expr
                     Expr::Index(x) | Expr::Dot(x) => {
-                        let (prop, expr, pos) = x.as_ref();
+                        let (sub_lhs, expr, pos) = x.as_ref();
-                        let args = &mut [target.as_mut(), &mut Default::default()];
 
-                        let (mut val, updated) = if let Expr::Property(p) = prop {
+                        match sub_lhs {
-                            let ((_, getter, _), _) = p.as_ref();
+                            // xxx.prop[expr] | xxx.prop.expr
-                            let args = &mut args[..1];
+                            Expr::Property(p) => {
-                            self.exec_fn_call(
+                                let ((_, getter, setter), _) = p.as_ref();
-                                state, lib, getter, true, 0, args, is_ref, true, None, level,
+                                let arg_values = &mut [target.as_mut(), &mut Default::default()];
-                            )
+                                let args = &mut arg_values[..1];
-                            .map_err(|err| err.new_position(*pos))?
+                                let (mut val, updated) = self
-                        } else {
+                                    .exec_fn_call(
-                            unreachable!();
+                                        state, lib, getter, true, 0, args, is_ref, true, None,
-                        };
+                                        level,
-                        let val = &mut val;
+                                    )
-                        let target = &mut val.into();
+                                    .map_err(|err| err.new_position(*pos))?;
 
-                        let (result, may_be_changed) = self
+                                let val = &mut val;
-                            .eval_dot_index_chain_helper(
+                                let target = &mut val.into();
-                                state, lib, this_ptr, target, expr, idx_values, next_chain, level,
-                                new_val,
-                            )
-                            .map_err(|err| err.new_position(*pos))?;
 
-                        // Feed the value back via a setter just in case it has been updated
+                                let (result, may_be_changed) = self
-                        if updated || may_be_changed {
+                                    .eval_dot_index_chain_helper(
-                            if let Expr::Property(p) = prop {
+                                        state, lib, this_ptr, target, expr, idx_values, next_chain,
-                                let ((_, _, setter), _) = p.as_ref();
+                                        level, new_val,
-                                // Re-use args because the first &mut parameter will not be consumed
+                                    )
-                                args[1] = val;
+                                    .map_err(|err| err.new_position(*pos))?;
-                                self.exec_fn_call(
+
-                                    state, lib, setter, true, 0, args, is_ref, true, None, level,
+                                // Feed the value back via a setter just in case it has been updated
-                                )
+                                if updated || may_be_changed {
-                                .or_else(|err| match *err {
+                                    // Re-use args because the first &mut parameter will not be consumed
-                                    // If there is no setter, no need to feed it back because the property is read-only
+                                    arg_values[1] = val;
-                                    EvalAltResult::ErrorDotExpr(_, _) => Ok(Default::default()),
+                                    self.exec_fn_call(
-                                    _ => Err(err.new_position(*pos)),
+                                        state, lib, setter, true, 0, arg_values, is_ref, true,
-                                })?;
+                                        None, level,
+                                    )
+                                    .or_else(
+                                        |err| match *err {
+                                            // If there is no setter, no need to feed it back because the property is read-only
+                                            EvalAltResult::ErrorDotExpr(_, _) => {
+                                                Ok(Default::default())
+                                            }
+                                            _ => Err(err.new_position(*pos)),
+                                        },
+                                    )?;
+                                }
+
+                                Ok((result, may_be_changed))
                             }
-                        }
+                            // xxx.fn_name(arg_expr_list)[expr] | xxx.fn_name(arg_expr_list).expr
+                            Expr::FnCall(x) if x.1.is_none() => {
+                                let (mut val, _) =
+                                    self.call_method(state, lib, target, sub_lhs, idx_val, level)?;
+                                let val = &mut val;
+                                let target = &mut val.into();
 
-                        Ok((result, may_be_changed))
+                                self.eval_dot_index_chain_helper(
+                                    state, lib, this_ptr, target, expr, idx_values, next_chain,
+                                    level, new_val,
+                                )
+                                .map_err(|err| err.new_position(*pos))
+                            }
+                            // xxx.module::fn_name(...) - syntax error
+                            Expr::FnCall(_) => unreachable!(),
+                            // Others - syntax error
+                            _ => unreachable!(),
+                        }
                     }
                     // Syntax error
                     _ => Err(Box::new(EvalAltResult::ErrorDotExpr(
@@ -1325,7 +1370,7 @@ impl Engine {
         let idx_values = &mut StaticVec::new();
 
         self.eval_indexed_chain(
-            scope, mods, state, lib, this_ptr, dot_rhs, idx_values, 0, level,
+            scope, mods, state, lib, this_ptr, dot_rhs, chain_type, idx_values, 0, level,
         )?;
 
         match dot_lhs {
@@ -1389,6 +1434,7 @@ impl Engine {
         lib: &Module,
         this_ptr: &mut Option<&mut Dynamic>,
         expr: &Expr,
+        chain_type: ChainType,
         idx_values: &mut StaticVec<Dynamic>,
         size: usize,
         level: usize,
@@ -1415,12 +1461,29 @@ impl Engine {
                 // Evaluate in left-to-right order
                 let lhs_val = match lhs {
                     Expr::Property(_) => Default::default(), // Store a placeholder in case of a property
+                    Expr::FnCall(x) if chain_type == ChainType::Dot && x.1.is_none() => {
+                        let arg_values = x
+                            .3
+                            .iter()
+                            .map(|arg_expr| {
+                                self.eval_expr(scope, mods, state, lib, this_ptr, arg_expr, level)
+                            })
+                            .collect::<Result<StaticVec<Dynamic>, _>>()?;
+
+                        Dynamic::from(arg_values)
+                    }
+                    Expr::FnCall(_) => unreachable!(),
                     _ => self.eval_expr(scope, mods, state, lib, this_ptr, lhs, level)?,
                 };
 
                 // Push in reverse order
+                let chain_type = match expr {
+                    Expr::Index(_) => ChainType::Index,
+                    Expr::Dot(_) => ChainType::Dot,
+                    _ => unreachable!(),
+                };
                 self.eval_indexed_chain(
-                    scope, mods, state, lib, this_ptr, rhs, idx_values, size, level,
+                    scope, mods, state, lib, this_ptr, rhs, chain_type, idx_values, size, level,
                 )?;
 
                 idx_values.push(lhs_val);