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-rw-r--r--docs/user-guide/06-interfaces-generics.md58
-rw-r--r--source/slang/slang-parser.cpp109
-rw-r--r--tests/language-feature/if-let/if-let-1.slang89
-rw-r--r--tests/language-feature/if-let/if-let-diagnose-1.slang53
-rw-r--r--tests/language-feature/if-let/if-let-diagnose.slang42
-rw-r--r--tests/language-feature/if-let/if-let.slang38
6 files changed, 388 insertions, 1 deletions
diff --git a/docs/user-guide/06-interfaces-generics.md b/docs/user-guide/06-interfaces-generics.md
index ba543df56..cb6a5070e 100644
--- a/docs/user-guide/06-interfaces-generics.md
+++ b/docs/user-guide/06-interfaces-generics.md
@@ -677,6 +677,64 @@ T compute<T>(T a1, T a2)
// compute(3, 1) == 2
```
+`as` operator can also be used in the `if` predicate to test if an object can be casted to a specific type, once the cast test is successful,
+the object can be used in the `if` block as the casted type without the need to retrieve the `Optional<T>::value` property:
+```csharp
+interface IFoo
+{
+ void foo();
+}
+
+struct MyImpl1 : IFoo
+{
+ void foo() { printf("MyImpl1");}
+}
+
+struct MyImpl2 : IFoo
+{
+ void foo() { printf("MyImpl2");}
+}
+
+struct MyImpl3 : IFoo
+{
+ void foo() { printf("MyImpl3");}
+}
+
+void test(IFoo foo)
+{
+ // This syntax will be desugared to the following:
+ // {
+ // Optional<MyImpl1> $OptVar = foo as MyImpl1;
+ // if ($OptVar.hasValue)
+ // {
+ // MyImpl1 t = $OptVar.value;
+ // t.foo();
+ // }
+ // else if ...
+ // }
+ if (let t = foo as MyImpl1) // t is of type MyImpl1
+ {
+ t.foo();
+ }
+ else if (let t = foo as MyImpl2) // t is of type MyImpl2
+ {
+ t.foo();
+ }
+ else
+ printf("fail");
+}
+
+void main()
+{
+ MyImpl1 v1;
+ test(v1);
+
+ MyImpl2 v2;
+ test(v2);
+}
+
+```
+
Extensions to Interfaces
-----------------------------
diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index e564b4956..2c304a663 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -199,6 +199,7 @@ namespace Slang
Stmt* parseLabelStatement();
DeclStmt* parseVarDeclrStatement(Modifiers modifiers);
IfStmt* parseIfStatement();
+ Stmt* parseIfLetStatement();
ForStmt* ParseForStatement();
WhileStmt* ParseWhileStatement();
DoWhileStmt* ParseDoWhileStatement();
@@ -5276,7 +5277,16 @@ namespace Slang
if (LookAheadToken(TokenType::LBrace))
statement = parseBlockStatement();
else if (LookAheadToken("if"))
- statement = parseIfStatement();
+ {
+ if(LookAheadToken("let", 2))
+ {
+ statement = parseIfLetStatement();
+ }
+ else
+ {
+ statement = parseIfStatement();
+ }
+ }
else if (LookAheadToken("for"))
statement = ParseForStatement();
else if (LookAheadToken("while"))
@@ -5579,6 +5589,103 @@ namespace Slang
return varDeclrStatement;
}
+ static Expr* constructIfLetPredicate(Parser* parser, VarExpr* varExpr)
+ {
+ // create a "var.hasValue" expression
+ MemberExpr* memberExpr = parser->astBuilder->create<MemberExpr>();
+ memberExpr->baseExpression = varExpr;
+ parser->FillPosition(memberExpr);
+ memberExpr->name = getName(parser, "hasValue");
+
+ return memberExpr;
+ }
+
+ // Parse the syntax 'if (let var = X as Y)'
+ Stmt* Parser::parseIfLetStatement()
+ {
+ ScopeDecl* scopeDecl = astBuilder->create<ScopeDecl>();
+ pushScopeAndSetParent(scopeDecl);
+
+ SeqStmt* newBody = astBuilder->create<SeqStmt>();
+
+ IfStmt* ifStatement = astBuilder->create<IfStmt>();
+ FillPosition(ifStatement);
+ ReadToken("if");
+ ReadToken(TokenType::LParent);
+
+ // parse 'let var = X as Y'
+ ReadToken("let");
+ auto identifierToken = ReadToken(TokenType::Identifier);
+ ReadToken(TokenType::OpAssign);
+ auto initExpr = ParseInitExpr();
+
+ // insert 'let tempVarDecl = X as Y;'
+ auto tempVarDecl = astBuilder->create<LetDecl>();
+ tempVarDecl->nameAndLoc = NameLoc(getName(this, "$OptVar"), identifierToken.loc);
+ tempVarDecl->initExpr = initExpr;
+ AddMember(currentScope->containerDecl, tempVarDecl);
+
+ DeclStmt* tmpVarDeclStmt = astBuilder->create<DeclStmt>();
+ FillPosition(tmpVarDeclStmt);
+ tmpVarDeclStmt->decl = tempVarDecl;
+ newBody->stmts.add(tmpVarDeclStmt);
+
+ // construct 'if (tempVarDecl.hasValue == true)'
+ VarExpr* tempVarExpr = astBuilder->create<VarExpr>();
+ tempVarExpr->scope = currentScope;
+ FillPosition(tempVarExpr);
+ tempVarExpr->name = tempVarDecl->getName();
+ ifStatement->predicate = constructIfLetPredicate(this, tempVarExpr);
+
+ ReadToken(TokenType::RParent);
+
+ // Create a new scope surrounding the positive statement, will be used for
+ // the variable declared in the if_let syntax
+ ScopeDecl* positiveScopeDecl = astBuilder->create<ScopeDecl>();
+ pushScopeAndSetParent(positiveScopeDecl);
+ ifStatement->positiveStatement = ParseStatement(ifStatement);
+ PopScope();
+
+ if (LookAheadToken("else"))
+ {
+ ReadToken("else");
+ ifStatement->negativeStatement = ParseStatement(ifStatement);
+ }
+
+ if (ifStatement->positiveStatement)
+ {
+ auto seqPositiveStmt = as<SeqStmt>(ifStatement->positiveStatement);
+ if (!seqPositiveStmt)
+ {
+ seqPositiveStmt = astBuilder->create<SeqStmt>();
+ }
+
+ MemberExpr* memberExpr = astBuilder->create<MemberExpr>();
+ memberExpr->baseExpression = tempVarExpr;
+ memberExpr->name = getName(this, "value");
+
+ auto varDecl = astBuilder->create<LetDecl>();
+ varDecl->nameAndLoc = NameLoc(identifierToken.getName(), identifierToken.loc);
+ varDecl->initExpr = memberExpr;
+
+ DeclStmt* varDeclrStatement = astBuilder->create<DeclStmt>();
+ varDeclrStatement->decl = varDecl;
+
+ // Add scope to the variable declared in the if_let syntax such
+ // that this variable cannot be used outside the positive statement
+ AddMember(positiveScopeDecl, varDecl);
+
+ seqPositiveStmt->stmts.add(varDeclrStatement);
+ seqPositiveStmt->stmts.add(ifStatement->positiveStatement);
+ ifStatement->positiveStatement = seqPositiveStmt;
+ }
+
+ newBody->stmts.add(ifStatement);
+ PopScope();
+
+ return newBody;
+ }
+
IfStmt* Parser::parseIfStatement()
{
IfStmt* ifStatement = astBuilder->create<IfStmt>();
diff --git a/tests/language-feature/if-let/if-let-1.slang b/tests/language-feature/if-let/if-let-1.slang
new file mode 100644
index 000000000..c197f26ea
--- /dev/null
+++ b/tests/language-feature/if-let/if-let-1.slang
@@ -0,0 +1,89 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -cpu -compute -shaderobj
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -cuda -compute -shaderobj
+//TEST(compute, vulkan):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -compute -shaderobj
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+
+interface IFoo
+{
+ int foo(int a);
+}
+
+struct MyImpl1 : IFoo
+{
+ int foo(int a) { return a; }
+}
+
+struct MyImpl2 : IFoo
+{
+ int foo(int a) { return a + 5; }
+}
+
+int test(IFoo foo, int idx)
+{
+ int val = 0;
+ if (let a = foo as MyImpl1)
+ {
+ val = a.foo(idx);
+ }
+ else if (let a = foo as MyImpl2)
+ {
+ val = a.foo(idx);
+ }
+ return (val);
+}
+
+int test1<T>(T t)
+{
+ if (let a = t as uint)
+ {
+ return 1;
+ }
+ else if(let a = t as float)
+ {
+ return 2;
+ }
+ else if (let a = t as double)
+ {
+ return 3;
+ }
+ else if (let a = t as int)
+ {
+ return 4;
+ }
+ else if (let a = t as uint64_t)
+ {
+ return 5;
+ }
+ else
+ {
+ return 6;
+ }
+}
+
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+ MyImpl1 impl1;
+ MyImpl2 impl2;
+ // CHECK: 1
+ // CHECK: 7
+ outputBuffer[0] = test(impl1, 1);
+ outputBuffer[1] = test(impl2, 2);
+
+ // CHECK: 1
+ outputBuffer[2] = test1(2U);
+ // CHECK: 2
+ outputBuffer[3] = test1(2.0f);
+ // CHECK: 3
+ outputBuffer[4] = test1(2.0lf);
+ // CHECK: 4
+ outputBuffer[5] = test1(2);
+ // CHECK: 5
+ outputBuffer[6] = test1(2LLU);
+ // CHECK: 6
+ outputBuffer[7] = test1(impl1);
+}
diff --git a/tests/language-feature/if-let/if-let-diagnose-1.slang b/tests/language-feature/if-let/if-let-diagnose-1.slang
new file mode 100644
index 000000000..2322abb1a
--- /dev/null
+++ b/tests/language-feature/if-let/if-let-diagnose-1.slang
@@ -0,0 +1,53 @@
+//TEST:SIMPLE(filecheck=CHECK): -target glsl -stage compute -entry computeMain
+//TEST:SIMPLE(filecheck=CHECK): -target hlsl -stage compute -entry computeMain
+//TEST:SIMPLE(filecheck=CHECK): -target cuda -stage compute -entry computeMain
+//TEST:SIMPLE(filecheck=CHECK): -target cpp -stage compute -entry computeMain
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+
+interface IFoo
+{
+ int foo(int a);
+}
+
+struct MyImpl : IFoo
+{
+ int foo(int a) { return a; }
+}
+
+struct MyImpl1 : IFoo
+{
+ int foo(int a) { return a; }
+}
+
+int test(IFoo foo, int idx)
+{
+ int val = 0;
+ if (let a = foo as MyImpl)
+ {
+ val = a.foo(idx);
+ }
+ // CHECK: error 30015: undefined identifier 'a'.
+ else if(a == none)
+ {
+ val = -1;
+ }
+ else
+ {
+ // CHECK: error 30015: undefined identifier 'a'.
+ if (a == none)
+ {
+ val = -1;
+ }
+ }
+ return (val);
+}
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+ MyImpl1 impl;
+ outputBuffer[dispatchThreadID.x] = test(impl, dispatchThreadID.x);
+}
diff --git a/tests/language-feature/if-let/if-let-diagnose.slang b/tests/language-feature/if-let/if-let-diagnose.slang
new file mode 100644
index 000000000..4e9aa69c7
--- /dev/null
+++ b/tests/language-feature/if-let/if-let-diagnose.slang
@@ -0,0 +1,42 @@
+//TEST:SIMPLE(filecheck=CHECK): -target glsl -stage compute -entry computeMain
+//TEST:SIMPLE(filecheck=CHECK): -target hlsl -stage compute -entry computeMain
+//TEST:SIMPLE(filecheck=CHECK): -target cuda -stage compute -entry computeMain
+//TEST:SIMPLE(filecheck=CHECK): -target cpp -stage compute -entry computeMain
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+
+interface IFoo
+{
+ int foo(int a);
+}
+
+struct MyImpl : IFoo
+{
+ int foo(int a) { return a; }
+}
+
+struct MyImpl1 : IFoo
+{
+ int foo(int a) { return a; }
+}
+
+int test(IFoo foo, int idx)
+{
+ int val = 0;
+ // CHECK: error 20002: syntax error.
+ if ((let a = foo as MyImpl))
+ {
+ val = a.foo(idx);
+ }
+ return (val);
+}
+
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+ MyImpl impl;
+ outputBuffer[dispatchThreadID.x] = test(impl, dispatchThreadID.x);
+}
diff --git a/tests/language-feature/if-let/if-let.slang b/tests/language-feature/if-let/if-let.slang
new file mode 100644
index 000000000..5bb31030f
--- /dev/null
+++ b/tests/language-feature/if-let/if-let.slang
@@ -0,0 +1,38 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -cpu -compute -shaderobj
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -cuda -compute -shaderobj
+//TEST(compute, vulkan):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -compute -shaderobj
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+
+
+interface IFoo
+{
+ int foo(int a);
+}
+
+struct MyImpl : IFoo
+{
+ int foo(int a) { return a; }
+}
+
+int test(IFoo foo, int idx)
+{
+ int val = 0;
+ if (let a = foo as MyImpl)
+ {
+ val = a.foo(idx);
+ }
+ return (val);
+}
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+ MyImpl impl;
+ // CHECK: 0
+ // CHECK: 1
+ // CHECK: 2
+ // CHECK: 3
+ outputBuffer[dispatchThreadID.x] = test(impl, dispatchThreadID.x);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2026-06-01 16:47:09 +0000