Allow duplicated switch cases.

CHANGELOG.md

@@ -14,10 +14,17 @@ New features
 Enhancements
 ------------
 
+### `switch` statement
+
 * `switch` cases can now include multiple values separated by `|`.
+* Duplicated `switch` cases are now allowed.
+* The error `ParseErrorType::DuplicatedSwitchCase` is deprecated.
+* Ranges in `switch` statements that are small (currently no more than 16 items) are unrolled if possible.
+
+### Others
+
 * `EvalContext::eval_expression_tree_raw` and `Expression::eval_with_context_raw` are added to allow for not rewinding the `Scope` at the end of a statements block.
 * A new `range` function variant that takes an exclusive range with a step.
-* Ranges in `switch` statements that are small (currently no more than 16 items) are unrolled if possible.
 
 
 Version 1.8.0

src/ast/mod.rs

@@ -22,8 +22,8 @@ pub use script_fn::EncapsulatedEnviron;
 #[cfg(not(feature = "no_function"))]
 pub use script_fn::{ScriptFnDef, ScriptFnMetadata};
 pub use stmt::{
-    ConditionalStmtBlock, OpAssignment, RangeCase, Stmt, StmtBlock, StmtBlockContainer,
+    CaseBlocksList, ConditionalStmtBlock, OpAssignment, RangeCase, Stmt, StmtBlock,
-    SwitchCases, TryCatchBlock,
+    StmtBlockContainer, SwitchCasesCollection, TryCatchBlock,
 };
 
 #[cfg(not(feature = "no_float"))]

src/ast/stmt.rs

@@ -176,14 +176,14 @@ impl fmt::Debug for RangeCase {
 impl From<Range<INT>> for RangeCase {
     #[inline(always)]
     fn from(value: Range<INT>) -> Self {
-        Self::ExclusiveInt(value, 0)
+        Self::ExclusiveInt(value, usize::MAX)
     }
 }
 
 impl From<RangeInclusive<INT>> for RangeCase {
     #[inline(always)]
     fn from(value: RangeInclusive<INT>) -> Self {
-        Self::InclusiveInt(value, 0)
+        Self::InclusiveInt(value, usize::MAX)
     }
 }
 
@@ -256,14 +256,16 @@ impl RangeCase {
     }
 }
 
+pub type CaseBlocksList = smallvec::SmallVec<[usize; 1]>;
+
 /// _(internals)_ A type containing all cases for a `switch` statement.
 /// Exported under the `internals` feature only.
 #[derive(Debug, Clone, Hash)]
-pub struct SwitchCases {
+pub struct SwitchCasesCollection {
     /// List of [`ConditionalStmtBlock`]'s.
-    pub blocks: StaticVec<ConditionalStmtBlock>,
+    pub case_blocks: StaticVec<ConditionalStmtBlock>,
     /// Dictionary mapping value hashes to [`ConditionalStmtBlock`]'s.
-    pub cases: BTreeMap<u64, usize>,
+    pub cases: BTreeMap<u64, CaseBlocksList>,
     /// Statements block for the default case (there can be no condition for the default case).
     pub def_case: usize,
     /// List of range cases.
@@ -512,7 +514,7 @@ pub enum Stmt {
     /// 0) Hash table for (condition, block)
     /// 1) Default block
     /// 2) List of ranges: (start, end, inclusive, condition, statement)
-    Switch(Box<(Expr, SwitchCases)>, Position),
+    Switch(Box<(Expr, SwitchCasesCollection)>, Position),
     /// `while` expr `{` stmt `}` | `loop` `{` stmt `}`
     ///
     /// If the guard expression is [`UNIT`][Expr::Unit], then it is a `loop` statement.
@@ -755,15 +757,18 @@ impl Stmt {
             Self::Switch(x, ..) => {
                 let (expr, sw) = &**x;
                 expr.is_pure()
-                    && sw.cases.values().all(|&c| {
+                    && sw.cases.values().flat_map(|cases| cases.iter()).all(|&c| {
-                        let block = &sw.blocks[c];
+                        let block = &sw.case_blocks[c];
                         block.condition.is_pure() && block.statements.iter().all(Stmt::is_pure)
                     })
                     && sw.ranges.iter().all(|r| {
-                        let block = &sw.blocks[r.index()];
+                        let block = &sw.case_blocks[r.index()];
                         block.condition.is_pure() && block.statements.iter().all(Stmt::is_pure)
                     })
-                    && sw.blocks[sw.def_case].statements.iter().all(Stmt::is_pure)
+                    && sw.case_blocks[sw.def_case]
+                        .statements
+                        .iter()
+                        .all(Stmt::is_pure)
             }
 
             // Loops that exit can be pure because it can never be infinite.
@@ -904,8 +909,9 @@ impl Stmt {
                 if !expr.walk(path, on_node) {
                     return false;
                 }
-                for (.., &b) in &sw.cases {
+                for (.., blocks) in &sw.cases {
-                    let block = &sw.blocks[b];
+                    for &b in blocks {
+                        let block = &sw.case_blocks[b];
 
                         if !block.condition.walk(path, on_node) {
                             return false;
@@ -916,8 +922,9 @@ impl Stmt {
                             }
                         }
                     }
+                }
                 for r in &sw.ranges {
-                    let block = &sw.blocks[r.index()];
+                    let block = &sw.case_blocks[r.index()];
 
                     if !block.condition.walk(path, on_node) {
                         return false;
@@ -928,7 +935,7 @@ impl Stmt {
                         }
                     }
                 }
-                for s in &sw.blocks[sw.def_case].statements {
+                for s in &sw.case_blocks[sw.def_case].statements {
                     if !s.walk(path, on_node) {
                         return false;
                     }

src/eval/stmt.rs

@@ -3,7 +3,7 @@
 use super::{Caches, EvalContext, GlobalRuntimeState, Target};
 use crate::api::events::VarDefInfo;
 use crate::ast::{
-    ASTFlags, BinaryExpr, Expr, Ident, OpAssignment, Stmt, SwitchCases, TryCatchBlock,
+    ASTFlags, BinaryExpr, Expr, Ident, OpAssignment, Stmt, SwitchCasesCollection, TryCatchBlock,
 };
 use crate::func::get_hasher;
 use crate::types::dynamic::{AccessMode, Union};
@@ -393,8 +393,8 @@ impl Engine {
             Stmt::Switch(x, ..) => {
                 let (
                     expr,
-                    SwitchCases {
+                    SwitchCasesCollection {
-                        blocks,
+                        case_blocks,
                         cases,
                         def_case,
                         ranges,
@@ -411,32 +411,49 @@ impl Engine {
                         let hash = hasher.finish();
 
                         // First check hashes
-                        if let Some(&case_block) = cases.get(&hash) {
+                        if let Some(case_blocks_list) = cases.get(&hash) {
-                            let case_block = &blocks[case_block];
+                            assert!(!case_blocks_list.is_empty());
 
-                            let cond_result = match case_block.condition {
+                            let mut result = Ok(None);
+
+                            for &index in case_blocks_list {
+                                let block = &case_blocks[index];
+
+                                let cond_result = match block.condition {
                                     Expr::BoolConstant(b, ..) => Ok(b),
                                     ref c => self
                                         .eval_expr(scope, global, caches, lib, this_ptr, c, level)
                                         .and_then(|v| {
                                             v.as_bool().map_err(|typ| {
-                                            self.make_type_mismatch_err::<bool>(typ, c.position())
+                                                self.make_type_mismatch_err::<bool>(
+                                                    typ,
+                                                    c.position(),
+                                                )
                                             })
                                         }),
                                 };
 
                                 match cond_result {
-                                Ok(true) => Ok(Some(&case_block.statements)),
+                                    Ok(true) => {
-                                Ok(false) => Ok(None),
+                                        result = Ok(Some(&block.statements));
-                                _ => cond_result.map(|_| None),
+                                        break;
                                     }
+                                    Ok(false) => (),
+                                    _ => {
+                                        result = cond_result.map(|_| None);
+                                        break;
+                                    }
+                                }
+                            }
+
+                            result
                         } else if value.is::<INT>() && !ranges.is_empty() {
                             // Then check integer ranges
                             let value = value.as_int().expect("`INT`");
                             let mut result = Ok(None);
 
                             for r in ranges.iter().filter(|r| r.contains(value)) {
-                                let block = &blocks[r.index()];
+                                let block = &case_blocks[r.index()];
 
                                 let cond_result = match block.condition {
                                     Expr::BoolConstant(b, ..) => Ok(b),
@@ -481,7 +498,7 @@ impl Engine {
                         }
                     } else if let Ok(None) = stmt_block_result {
                         // Default match clause
-                        let def_case = &blocks[*def_case].statements;
+                        let def_case = &case_blocks[*def_case].statements;
 
                         if !def_case.is_empty() {
                             self.eval_stmt_block(

src/lib.rs

@@ -285,7 +285,7 @@ pub use parser::ParseState;
 #[cfg(feature = "internals")]
 pub use ast::{
     ASTFlags, ASTNode, BinaryExpr, ConditionalStmtBlock, Expr, FnCallExpr, FnCallHashes, Ident,
-    OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlock, SwitchCases, TryCatchBlock,
+    OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlock, SwitchCasesCollection, TryCatchBlock,
 };
 
 #[cfg(feature = "internals")]

src/optimizer.rs

@@ -1,7 +1,9 @@
 //! Module implementing the [`AST`] optimizer.
 #![cfg(not(feature = "no_optimize"))]
 
-use crate::ast::{ASTFlags, Expr, OpAssignment, Stmt, StmtBlock, StmtBlockContainer, SwitchCases};
+use crate::ast::{
+    ASTFlags, Expr, OpAssignment, Stmt, StmtBlock, StmtBlockContainer, SwitchCasesCollection,
+};
 use crate::engine::{KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_PRINT, KEYWORD_TYPE_OF};
 use crate::eval::{Caches, GlobalRuntimeState};
 use crate::func::builtin::get_builtin_binary_op_fn;
@@ -524,8 +526,8 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
         Stmt::Switch(x, pos) if x.0.is_constant() => {
             let (
                 match_expr,
-                SwitchCases {
+                SwitchCasesCollection {
-                    blocks,
+                    case_blocks,
                     cases,
                     ranges,
                     def_case,
@@ -538,25 +540,30 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
             let hash = hasher.finish();
 
             // First check hashes
-            if let Some(b) = cases.remove(&hash) {
+            if let Some(case_blocks_list) = cases.get(&hash) {
-                let mut b = mem::take(&mut blocks[b]);
+                match &case_blocks_list[..] {
+                    [] => (),
+                    [index] => {
+                        let mut b = mem::take(&mut case_blocks[*index]);
                         cases.clear();
 
                         match b.condition {
                             Expr::BoolConstant(true, ..) => {
                                 // Promote the matched case
                                 let statements: StmtBlockContainer = mem::take(&mut b.statements);
-                        let statements = optimize_stmt_block(statements, state, true, true, false);
+                                let statements =
+                                    optimize_stmt_block(statements, state, true, true, false);
                                 *stmt = (statements, b.statements.span()).into();
                             }
                             ref mut condition => {
                                 // switch const { case if condition => stmt, _ => def } => if condition { stmt } else { def }
                                 optimize_expr(condition, state, false);
 
-                        let def_case = &mut blocks[*def_case].statements;
+                                let def_case = &mut case_blocks[*def_case].statements;
                                 let def_span = def_case.span_or_else(*pos, Position::NONE);
                                 let def_case: StmtBlockContainer = mem::take(def_case);
-                        let def_stmt = optimize_stmt_block(def_case, state, true, true, false);
+                                let def_stmt =
+                                    optimize_stmt_block(def_case, state, true, true, false);
                                 *stmt = Stmt::If(
                                     (
                                         mem::take(condition),
@@ -572,6 +579,27 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
                         state.set_dirty();
                         return;
                     }
+                    _ => {
+                        for &index in case_blocks_list {
+                            let mut b = mem::take(&mut case_blocks[index]);
+
+                            match b.condition {
+                                Expr::BoolConstant(true, ..) => {
+                                    // Promote the matched case
+                                    let statements: StmtBlockContainer =
+                                        mem::take(&mut b.statements);
+                                    let statements =
+                                        optimize_stmt_block(statements, state, true, true, false);
+                                    *stmt = (statements, b.statements.span()).into();
+                                    state.set_dirty();
+                                    return;
+                                }
+                                _ => (),
+                            }
+                        }
+                    }
+                }
+            }
 
             // Then check ranges
             if value.is::<INT>() && !ranges.is_empty() {
@@ -580,16 +608,19 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
                 // Only one range or all ranges without conditions
                 if ranges.len() == 1
                     || ranges.iter().all(|r| {
-                        matches!(blocks[r.index()].condition, Expr::BoolConstant(true, ..))
+                        matches!(
+                            case_blocks[r.index()].condition,
+                            Expr::BoolConstant(true, ..)
+                        )
                     })
                 {
                     for r in ranges.iter().filter(|r| r.contains(value)) {
-                        let condition = mem::take(&mut blocks[r.index()].condition);
+                        let condition = mem::take(&mut case_blocks[r.index()].condition);
 
                         match condition {
                             Expr::BoolConstant(true, ..) => {
                                 // Promote the matched case
-                                let block = &mut blocks[r.index()];
+                                let block = &mut case_blocks[r.index()];
                                 let statements = mem::take(&mut *block.statements);
                                 let statements =
                                     optimize_stmt_block(statements, state, true, true, false);
@@ -599,13 +630,13 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
                                 // switch const { range if condition => stmt, _ => def } => if condition { stmt } else { def }
                                 optimize_expr(&mut condition, state, false);
 
-                                let def_case = &mut blocks[*def_case].statements;
+                                let def_case = &mut case_blocks[*def_case].statements;
                                 let def_span = def_case.span_or_else(*pos, Position::NONE);
                                 let def_case: StmtBlockContainer = mem::take(def_case);
                                 let def_stmt =
                                     optimize_stmt_block(def_case, state, true, true, false);
 
-                                let statements = mem::take(&mut blocks[r.index()].statements);
+                                let statements = mem::take(&mut case_blocks[r.index()].statements);
 
                                 *stmt = Stmt::If(
                                     (
@@ -638,7 +669,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
                     }
 
                     for r in &*ranges {
-                        let b = &mut blocks[r.index()];
+                        let b = &mut case_blocks[r.index()];
                         let statements = mem::take(&mut *b.statements);
                         *b.statements =
                             optimize_stmt_block(statements, state, preserve_result, true, false);
@@ -659,7 +690,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
 
             // Promote the default case
             state.set_dirty();
-            let def_case = &mut blocks[*def_case].statements;
+            let def_case = &mut case_blocks[*def_case].statements;
             let def_span = def_case.span_or_else(*pos, Position::NONE);
             let def_case: StmtBlockContainer = mem::take(def_case);
             let def_stmt = optimize_stmt_block(def_case, state, true, true, false);
@@ -669,8 +700,8 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
         Stmt::Switch(x, ..) => {
             let (
                 match_expr,
-                SwitchCases {
+                SwitchCasesCollection {
-                    blocks,
+                    case_blocks,
                     cases,
                     ranges,
                     def_case,
@@ -681,7 +712,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
             optimize_expr(match_expr, state, false);
 
             // Optimize blocks
-            for b in blocks.iter_mut() {
+            for b in case_blocks.iter_mut() {
                 let statements = mem::take(&mut *b.statements);
                 *b.statements =
                     optimize_stmt_block(statements, state, preserve_result, true, false);
@@ -704,15 +735,31 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
             }
 
             // Remove false cases
-            cases.retain(|_, &mut block| match blocks[block].condition {
+            let cases_len = cases.len();
-                Expr::BoolConstant(false, ..) => {
+            cases.retain(|_, list| {
-                    state.set_dirty();
+                // Remove all entries that have false conditions
-                    false
+                list.retain(|index| match case_blocks[*index].condition {
-                }
+                    Expr::BoolConstant(false, ..) => false,
                     _ => true,
                 });
+                // Remove all entries after a `true` condition
+                if let Some(n) = list
+                    .iter()
+                    .find(|&&index| match case_blocks[index].condition {
+                        Expr::BoolConstant(true, ..) => true,
+                        _ => false,
+                    })
+                {
+                    list.truncate(n + 1);
+                }
+                // Remove if no entry left
+                !list.is_empty()
+            });
+            if cases.len() != cases_len {
+                state.set_dirty();
+            }
             // Remove false ranges
-            ranges.retain(|r| match blocks[r.index()].condition {
+            ranges.retain(|r| match case_blocks[r.index()].condition {
                 Expr::BoolConstant(false, ..) => {
                     state.set_dirty();
                     false
@@ -720,20 +767,20 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
                 _ => true,
             });
 
-            let def_stmt_block = &mut blocks[*def_case].statements;
+            let def_stmt_block = &mut case_blocks[*def_case].statements;
             let def_block = mem::take(&mut **def_stmt_block);
             **def_stmt_block = optimize_stmt_block(def_block, state, preserve_result, true, false);
 
             // Remove unused block statements
-            for index in 0..blocks.len() {
+            for index in 0..case_blocks.len() {
                 if *def_case == index
-                    || cases.values().any(|&n| n == index)
+                    || cases.values().flat_map(|c| c.iter()).any(|&n| n == index)
                     || ranges.iter().any(|r| r.index() == index)
                 {
                     continue;
                 }
 
-                let b = &mut blocks[index];
+                let b = &mut case_blocks[index];
 
                 if !b.statements.is_empty() {
                     b.statements = StmtBlock::NONE;

src/parser.rs

@@ -3,8 +3,9 @@
 use crate::api::events::VarDefInfo;
 use crate::api::options::LangOptions;
 use crate::ast::{
-    ASTFlags, BinaryExpr, ConditionalStmtBlock, Expr, FnCallExpr, FnCallHashes, Ident,
+    ASTFlags, BinaryExpr, CaseBlocksList, ConditionalStmtBlock, Expr, FnCallExpr, FnCallHashes,
-    OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlockContainer, SwitchCases, TryCatchBlock,
+    Ident, OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlockContainer, SwitchCasesCollection,
+    TryCatchBlock,
 };
 use crate::engine::{Precedence, KEYWORD_THIS, OP_CONTAINS};
 use crate::eval::GlobalRuntimeState;
@@ -1054,11 +1055,11 @@ impl Engine {
             }
         }
 
-        let mut blocks = StaticVec::<ConditionalStmtBlock>::new();
+        let mut case_blocks = StaticVec::<ConditionalStmtBlock>::new();
-        let mut cases = BTreeMap::<u64, usize>::new();
+        let mut cases = BTreeMap::<u64, CaseBlocksList>::new();
         let mut ranges = StaticVec::<RangeCase>::new();
-        let mut def_pos = Position::NONE;
+        let mut def_stmt_pos = Position::NONE;
-        let mut def_stmt = None;
+        let mut def_stmt_index = None;
 
         loop {
             const MISSING_RBRACE: &str = "to end this switch block";
@@ -1074,8 +1075,8 @@ impl Engine {
                             .into_err(*pos),
                     )
                 }
-                (Token::Underscore, pos) if def_stmt.is_none() => {
+                (Token::Underscore, pos) if def_stmt_index.is_none() => {
-                    def_pos = *pos;
+                    def_stmt_pos = *pos;
                     eat_token(input, Token::Underscore);
 
                     let (if_clause, if_pos) = match_token(input, Token::If);
@@ -1086,10 +1087,8 @@ impl Engine {
 
                     (Default::default(), Expr::BoolConstant(true, Position::NONE))
                 }
-                (Token::Underscore, pos) => return Err(PERR::DuplicatedSwitchCase.into_err(*pos)),
+                _ if def_stmt_index.is_some() => {
-
+                    return Err(PERR::WrongSwitchDefaultCase.into_err(def_stmt_pos))
-                _ if def_stmt.is_some() => {
-                    return Err(PERR::WrongSwitchDefaultCase.into_err(def_pos))
                 }
 
                 _ => {
@@ -1143,8 +1142,8 @@ impl Engine {
             let need_comma = !stmt.is_self_terminated();
             let has_condition = !matches!(condition, Expr::BoolConstant(true, ..));
 
-            blocks.push((condition, stmt).into());
+            case_blocks.push((condition, stmt).into());
-            let index = blocks.len() - 1;
+            let index = case_blocks.len() - 1;
 
             if !case_expr_list.is_empty() {
                 for expr in case_expr_list {
@@ -1170,7 +1169,10 @@ impl Engine {
                                 for n in r {
                                     let hasher = &mut get_hasher();
                                     Dynamic::from_int(n).hash(hasher);
-                                    cases.entry(hasher.finish()).or_insert(index);
+                                    cases
+                                        .entry(hasher.finish())
+                                        .and_modify(|cases| cases.push(index))
+                                        .or_insert_with(|| [index].into());
                                 }
                             } else {
                                 // Other range
@@ -1189,13 +1191,13 @@ impl Engine {
                     value.hash(hasher);
                     let hash = hasher.finish();
 
-                    if cases.contains_key(&hash) {
+                    cases
-                        return Err(PERR::DuplicatedSwitchCase.into_err(expr.start_position()));
+                        .entry(hash)
-                    }
+                        .and_modify(|cases| cases.push(index))
-                    cases.insert(hash, index);
+                        .or_insert_with(|| [index].into());
                 }
             } else {
-                def_stmt = Some(index);
+                def_stmt_index = Some(index);
             }
 
             match input.peek().expect(NEVER_ENDS) {
@@ -1221,13 +1223,13 @@ impl Engine {
             }
         }
 
-        let def_case = def_stmt.unwrap_or_else(|| {
+        let def_case = def_stmt_index.unwrap_or_else(|| {
-            blocks.push(Default::default());
+            case_blocks.push(Default::default());
-            blocks.len() - 1
+            case_blocks.len() - 1
         });
 
-        let cases = SwitchCases {
+        let cases = SwitchCasesCollection {
-            blocks,
+            case_blocks,
             cases,
             def_case,
             ranges,

src/types/parse_error.rs

@@ -97,6 +97,14 @@ pub enum ParseErrorType {
     /// A map definition has duplicated property names. Wrapped value is the property name.
     DuplicatedProperty(String),
     /// A `switch` case is duplicated.
+    ///
+    /// # Deprecated
+    ///
+    /// This error variant is deprecated. It never occurs and will be removed in the next major version.
+    #[deprecated(
+        since = "1.9.0",
+        note = "This error variant is deprecated. It never occurs and will be removed in the next major version."
+    )]
     DuplicatedSwitchCase,
     /// A variable name is duplicated. Wrapped value is the variable name.
     DuplicatedVariable(String),
@@ -211,6 +219,7 @@ impl fmt::Display for ParseErrorType {
             Self::FnDuplicatedParam(s, arg) => write!(f, "Duplicated parameter {} for function {}", arg, s),
 
             Self::DuplicatedProperty(s) => write!(f, "Duplicated property for object map literal: {}", s),
+            #[allow(deprecated)]
             Self::DuplicatedSwitchCase => f.write_str("Duplicated switch case"),
             Self::DuplicatedVariable(s) => write!(f, "Duplicated variable name: {}", s),
 

tests/switch.rs

@@ -32,7 +32,6 @@ fn test_switch() -> Result<(), Box<EvalAltResult>> {
         )?,
         'a'
     );
-
     assert_eq!(
         engine.eval_with_scope::<bool>(&mut scope, "switch x { 1 => (), 2 => 'a', 42 => true }")?,
         true
@@ -98,6 +97,16 @@ fn test_switch() -> Result<(), Box<EvalAltResult>> {
         3
     );
 
+    assert_eq!(
+        engine.eval_with_scope::<INT>(&mut scope, "switch 42 { 42 => 123, 42 => 999 }")?,
+        123
+    );
+
+    assert_eq!(
+        engine.eval_with_scope::<INT>(&mut scope, "switch x { 42 => 123, 42 => 999 }")?,
+        123
+    );
+
     Ok(())
 }
 
@@ -105,13 +114,6 @@ fn test_switch() -> Result<(), Box<EvalAltResult>> {
 fn test_switch_errors() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
 
-    assert!(matches!(
-        *engine
-            .compile("switch x { 1 => 123, 1 => 42 }")
-            .expect_err("should error")
-            .0,
-        ParseErrorType::DuplicatedSwitchCase
-    ));
     assert!(matches!(
         *engine
             .compile("switch x { _ => 123, 1 => 42 }")
@@ -159,23 +161,22 @@ fn test_switch_condition() -> Result<(), Box<EvalAltResult>> {
         9
     );
 
-    assert!(matches!(
+    assert_eq!(
-        *engine
+        engine.eval_with_scope::<INT>(
-            .compile(
+            &mut scope,
             "
                 switch x {
-                        21 if x < 40 => 1,
+                    42 if x < 40 => 1,
-                        21 if x == 10 => 10,
+                    42 if x > 40 => 7,
                     0 if x < 100 => 2,
                     1 => 3,
+                    42 if x == 10 => 10,
                     _ => 9
                 }
             "
-            )
+        )?,
-            .expect_err("should error")
+        7
-            .0,
+    );
-        ParseErrorType::DuplicatedSwitchCase
-    ));
 
     assert!(matches!(
         *engine