Allow explicit selection of backend

1 files changed, 16 insertions, 2 deletions

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 {