src/main/java/org/zwobble/couscous/backends/python/PythonBackend.java


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package org.zwobble.couscous.backends.python;

import com.google.common.collect.ImmutableList;
import com.google.common.io.Resources;
import org.zwobble.couscous.Backend;
import org.zwobble.couscous.ast.TypeNode;

import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.List;

import static org.zwobble.couscous.backends.python.PythonCodeGenerator.generateCode;
import static org.zwobble.couscous.backends.python.PythonSerializer.serialize;
import static org.zwobble.couscous.util.ExtraLists.list;

public class PythonBackend implements Backend {
    private static final List<String> RUNTIME_FILES = ImmutableList.of(
        "java.lang.Object",
        "java.lang.Boolean",
        "java.lang.Integer",
        "java.lang.String",
        "_couscous");
    
    private final Path root;
    private final String packageName;
    
    public PythonBackend(Path root, String packageName) {
        this.root = root;
        this.packageName = packageName;
    }
    
    @Override
    public void compile(List<TypeNode> classes) throws IOException {
        for (TypeNode classNode : classes) {
            compileClass(classNode);
        }
        for (String runtimeFile :  RUNTIME_FILES) {
            String path = relativePathForModule(runtimeFile);
            writeModule(
                runtimeFile,
                Resources.toString(Resources.getResource("python/runtime/" + path), StandardCharsets.UTF_8));
        }
    }
    
    private Path destinationPathForModule(String moduleName) {
        return root.resolve(packageName).resolve(relativePathForModule(moduleName));
    }
    
    private String relativePathForModule(String moduleName) {
        return moduleName.replace(".", File.separator) + ".py";
    }
    
    private void compileClass(TypeNode classNode) throws IOException {
        writeModule(
            classNode.getName().getQualifiedName(),
            serialize(generateCode(classNode)));
    }
    
    private void writeModule(String name, String contents) throws IOException {
        Path path = destinationPathForModule(name);
        Files.createDirectories(path.getParent());
        createPythonPackages(path.getParent());
        Files.write(path, list(contents));
    }
    
    private void createPythonPackages(Path packagePath) throws IOException {
        while (packagePath.startsWith(root)) {
            final java.nio.file.Path packageFile = packagePath.resolve("__init__.py");
            if (!packageFile.toFile().exists()) {
                Files.createFile(packageFile);
            }
            packagePath = packagePath.getParent();
        }
    }
}