Allow explicit selection of backend

9 files changed, 104 insertions, 22 deletions

diff --git a/src/main/java/org/shedlang/compiler/backends/BackendFactory.java b/src/main/java/org/shedlang/compiler/backends/BackendFactory.java
index b8fcdb46..66b0bc9d 100644
--- a/src/main/java/org/shedlang/compiler/backends/BackendFactory.java
+++ b/src/main/java/org/shedlang/compiler/backends/BackendFactory.java
@@ -3,5 +3,6 @@ package org.shedlang.compiler.backends;
 import java.util.Optional;
 
 public interface BackendFactory {
+    String name();
     Optional<Backend> backendForTarget(ShedTarget target);
 }
diff --git a/src/main/java/org/shedlang/compiler/backends/Backends.java b/src/main/java/org/shedlang/compiler/backends/Backends.java
index d266302f..333f73ad 100644
--- a/src/main/java/org/shedlang/compiler/backends/Backends.java
+++ b/src/main/java/org/shedlang/compiler/backends/Backends.java
@@ -1,9 +1,11 @@
 package org.shedlang.compiler.backends;
 
+import org.shedlang.compiler.backends.cranelift.CraneliftBackendFactory;
 import org.shedlang.compiler.backends.llvm.LlvmBackendFactory;
 import org.shedlang.compiler.backends.wasm.WasmBackendFactory;
 
 import java.util.List;
+import java.util.Optional;
 
 public class Backends {
     private Backends() {
@@ -12,19 +14,25 @@ public class Backends {
     private static final List<BackendFactory> BACKEND_FACTORIES = List.of(
         new LlvmBackendFactory(),
         new WasmBackendFactory(),
+        new CraneliftBackendFactory(),
         PatioNativeCHeadersBackend.FACTORY,
         PatioTextBackend.FACTORY,
         ShidTextBackend.FACTORY
     );
 
-    public static List<String> targetNames() {
-        return ShedTarget.targetNames();
+    public static List<String> backendNames() {
+        return BACKEND_FACTORIES.stream()
+            .map(factory -> factory.name())
+            .toList();
     }
 
-    public static Backend backendForTarget(String targetName) {
-        var target = ShedTarget.fromString(targetName)
-            .orElseThrow(() -> new UnsupportedOperationException("TODO"));
+    public static Optional<BackendFactory> backendFactory(String backendName) {
+        return BACKEND_FACTORIES.stream()
+            .filter(factory -> factory.name().equals(backendName))
+            .findFirst();
+    }
 
+    public static Backend backendForTarget(ShedTarget target) {
         for (var factory : BACKEND_FACTORIES) {
             var backend = factory.backendForTarget(target);
             if (backend.isPresent()) {
diff --git a/src/main/java/org/shedlang/compiler/backends/PatioNativeCHeadersBackend.java b/src/main/java/org/shedlang/compiler/backends/PatioNativeCHeadersBackend.java
index ea8bde7c..84f7332a 100644
--- a/src/main/java/org/shedlang/compiler/backends/PatioNativeCHeadersBackend.java
+++ b/src/main/java/org/shedlang/compiler/backends/PatioNativeCHeadersBackend.java
@@ -16,11 +16,19 @@ import java.util.List;
 import java.util.Optional;
 
 public class PatioNativeCHeadersBackend implements Backend {
-    public static final BackendFactory FACTORY = target -> {
-        if (target == ShedTarget.PATIO_NATIVE_C_HEADERS) {
-            return Optional.of(PatioNativeCHeadersBackend.INSTANCE);
-        } else {
-            return Optional.empty();
+    public static final BackendFactory FACTORY = new BackendFactory() {
+        @Override
+        public String name() {
+            return "patio-native-c-headers";
+        }
+
+        @Override
+        public Optional<Backend> backendForTarget(ShedTarget target) {
+            if (target == ShedTarget.PATIO_NATIVE_C_HEADERS) {
+                return Optional.of(PatioNativeCHeadersBackend.INSTANCE);
+            } else {
+                return Optional.empty();
+            }
         }
     };
 
diff --git a/src/main/java/org/shedlang/compiler/backends/PatioTextBackend.java b/src/main/java/org/shedlang/compiler/backends/PatioTextBackend.java
index c2fe8708..e93c7644 100644
--- a/src/main/java/org/shedlang/compiler/backends/PatioTextBackend.java
+++ b/src/main/java/org/shedlang/compiler/backends/PatioTextBackend.java
@@ -16,11 +16,19 @@ import java.util.List;
 import java.util.Optional;
 
 public class PatioTextBackend implements Backend {
-    public static final BackendFactory FACTORY = target -> {
-        if (target == ShedTarget.PATIO_TEXT) {
-            return Optional.of(PatioTextBackend.INSTANCE);
-        } else {
-            return Optional.empty();
+    public static final BackendFactory FACTORY = new BackendFactory() {
+        @Override
+        public String name() {
+            return "patio-text";
+        }
+
+        @Override
+        public Optional<Backend> backendForTarget(ShedTarget target) {
+            if (target == ShedTarget.PATIO_TEXT) {
+                return Optional.of(PatioTextBackend.INSTANCE);
+            } else {
+                return Optional.empty();
+            }
         }
     };
 
diff --git a/src/main/java/org/shedlang/compiler/backends/ShidTextBackend.java b/src/main/java/org/shedlang/compiler/backends/ShidTextBackend.java
index 7468336f..56174101 100644
--- a/src/main/java/org/shedlang/compiler/backends/ShidTextBackend.java
+++ b/src/main/java/org/shedlang/compiler/backends/ShidTextBackend.java
@@ -13,11 +13,19 @@ import java.util.List;
 import java.util.Optional;
 
 public class ShidTextBackend implements Backend {
-    public static final BackendFactory FACTORY = target -> {
-        if (target == ShedTarget.SHID_TEXT) {
-            return Optional.of(ShidTextBackend.INSTANCE);
-        } else {
-            return Optional.empty();
+    public static final BackendFactory FACTORY = new BackendFactory() {
+        @Override
+        public String name() {
+            return "shid-text";
+        }
+
+        @Override
+        public Optional<Backend> backendForTarget(ShedTarget target) {
+            if (target == ShedTarget.SHID_TEXT) {
+                return Optional.of(ShidTextBackend.INSTANCE);
+            } else {
+                return Optional.empty();
+            }
         }
     };
 
diff --git a/src/main/java/org/shedlang/compiler/backends/cranelift/CraneliftBackendFactory.java b/src/main/java/org/shedlang/compiler/backends/cranelift/CraneliftBackendFactory.java
new file mode 100644
index 00000000..b933d975
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/backends/cranelift/CraneliftBackendFactory.java
@@ -0,0 +1,25 @@
+package org.shedlang.compiler.backends.cranelift;
+
+import org.shedlang.compiler.backends.Backend;
+import org.shedlang.compiler.backends.BackendFactory;
+import org.shedlang.compiler.backends.ShedTarget;
+import org.shedlang.compiler.backends.llvm.LlvmTarget;
+
+import java.util.Optional;
+
+public class CraneliftBackendFactory implements BackendFactory {
+    @Override
+    public String name() {
+        return "cranelift";
+    }
+
+    @Override
+    public Optional<Backend> backendForTarget(ShedTarget target) {
+        Optional<LlvmTarget> llvmTarget = switch (target) {
+            case AMD64 -> Optional.of(LlvmTarget.AMD64);
+            default -> Optional.empty();
+        };
+
+        return llvmTarget.map(CraneliftBackend::forTarget);
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmBackendFactory.java b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmBackendFactory.java
index bb8a952a..301a912b 100644
--- a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmBackendFactory.java
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmBackendFactory.java
@@ -8,6 +8,11 @@ import java.util.Optional;
 
 public class LlvmBackendFactory implements BackendFactory {
     @Override
+    public String name() {
+        return "llvm";
+    }
+
+    @Override
     public Optional<Backend> backendForTarget(ShedTarget target) {
         Optional<LlvmTarget> llvmTarget = switch (target) {
             case AMD64 -> Optional.of(LlvmTarget.AMD64);
diff --git a/src/main/java/org/shedlang/compiler/backends/wasm/WasmBackendFactory.java b/src/main/java/org/shedlang/compiler/backends/wasm/WasmBackendFactory.java
index 5cf8446f..439bc05d 100644
--- a/src/main/java/org/shedlang/compiler/backends/wasm/WasmBackendFactory.java
+++ b/src/main/java/org/shedlang/compiler/backends/wasm/WasmBackendFactory.java
@@ -8,6 +8,11 @@ import java.util.Optional;
 
 public class WasmBackendFactory implements BackendFactory {
     @Override
+    public String name() {
+        return "wasm";
+    }
+
+    @Override
     public Optional<Backend> backendForTarget(ShedTarget target) {
         Optional<WasmTarget> wasmTarget = switch (target) {
             case WASM32 -> Optional.of(WasmTarget.WASM32);
diff --git a/src/main/java/org/shedlang/compiler/cli/ShedCli.java b/src/main/java/org/shedlang/compiler/cli/ShedCli.java
index 46bf9b5f..e4f98607 100644
--- a/src/main/java/org/shedlang/compiler/cli/ShedCli.java
+++ b/src/main/java/org/shedlang/compiler/cli/ShedCli.java
@@ -6,6 +6,7 @@ import net.sourceforge.argparse4j.inf.ArgumentParserException;
 import net.sourceforge.argparse4j.inf.Namespace;
 import org.shedlang.compiler.ShedCompiler;
 import org.shedlang.compiler.backends.Backends;
+import org.shedlang.compiler.backends.ShedTarget;
 import org.shedlang.compiler.errors.CompilerError;
 
 import java.io.IOException;
@@ -31,7 +32,19 @@ public class ShedCli {
 
         switch (args.<Command>get("command")) {
             case COMPILE -> {
-                var backend = Backends.backendForTarget(args.getString("target"));
+                var target = ShedTarget.fromString(args.getString("target")).orElseThrow();
+                var backend = Optional.ofNullable(args.getString("backend"))
+                    .map(
+                        backendName ->
+                            Backends
+                                .backendFactory(backendName)
+                                // In principle, this should be prevented by the arg parsing.
+                                .orElseThrow(() -> new UnsupportedOperationException("Unrecognised backend: " + backendName))
+                                .backendForTarget(target)
+                                // TODO: better error
+                                .orElseThrow(() -> new UnsupportedOperationException("Backend " + backendName + " does not support target " + target.targetName()))
+                    )
+                    .orElseGet(() -> Backends.backendForTarget(target));
                 var profile = Optional.ofNullable(args.getString("profile"));
                 compiler.compile(sourcePath, backend, profile);
             }
@@ -50,7 +63,8 @@ public class ShedCli {
             .addArgument("source")
             .type(new PathArgumentType())
             .required(true);
-        compileSubParser.addArgument("--target").choices(Backends.targetNames()).required(true);
+        compileSubParser.addArgument("--backend").choices(Backends.backendNames()).required(false);
+        compileSubParser.addArgument("--target").choices(ShedTarget.targetNames()).required(true);
         compileSubParser.addArgument("--profile").required(false);
 
         try {