Add the beginnings of a Python backend

13 files changed, 274 insertions, 0 deletions

diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonBlock.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonBlock.java
new file mode 100644
index 0000000..8bc7132
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonBlock.java
@@ -0,0 +1,25 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import java.util.Iterator;
+import java.util.List;
+
+import com.google.common.collect.ImmutableList;
+
+import static java.util.Arrays.asList;
+
+public class PythonBlock implements Iterable<PythonStatementNode> {
+    private final List<PythonStatementNode> statements;
+
+    public PythonBlock(List<? extends PythonStatementNode> statements) {
+        if (statements.isEmpty()) {
+            this.statements = asList(PythonPassNode.PASS);
+        } else {
+            this.statements = ImmutableList.copyOf(statements);   
+        }
+    }
+
+    @Override
+    public Iterator<PythonStatementNode> iterator() {
+        return statements.iterator();
+    }
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonClassNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonClassNode.java
new file mode 100644
index 0000000..958a21a
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonClassNode.java
@@ -0,0 +1,48 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import java.util.List;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+import com.google.common.collect.ImmutableList;
+
+import lombok.Value;
+
+@Value(staticConstructor="pythonClass")
+public class PythonClassNode implements PythonStatementNode {
+    public static Builder builder(String name) {
+        return new Builder(name);
+    }
+    
+    public static class Builder {
+        private final String name;
+        private final ImmutableList.Builder<PythonStatementNode> statements;
+
+        public Builder(String name) {
+            this.name = name;
+            this.statements = ImmutableList.builder();
+        }
+        
+        public PythonClassNode build() {
+            return new PythonClassNode(name, new PythonBlock(statements.build()));
+        }
+
+        public Builder statement(PythonStatementNode statement) {
+            statements.add(statement);
+            return this;
+        }
+    }
+    
+    public static PythonClassNode pythonClass(String name, List<? extends PythonStatementNode> body) {
+        return new PythonClassNode(name, new PythonBlock(body));
+    }
+    
+    String name;
+    PythonBlock body;
+    
+    @Override
+    public <T> T accept(PythonNodeVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonExpressionNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonExpressionNode.java
new file mode 100644
index 0000000..9c8a259
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonExpressionNode.java
@@ -0,0 +1,5 @@
+package org.zwobble.couscous.backends.python.ast;
+
+public interface PythonExpressionNode extends PythonNode {
+
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonFunctionDefinitionNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonFunctionDefinitionNode.java
new file mode 100644
index 0000000..6d66df8
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonFunctionDefinitionNode.java
@@ -0,0 +1,22 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import java.util.List;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+import lombok.Value;
+
+@Value(staticConstructor="pythonFunctionDefinition")
+public class PythonFunctionDefinitionNode implements PythonStatementNode {
+    public static PythonFunctionDefinitionNode pythonFunctionDefinition(String name, List<PythonStatementNode> body) {
+        return pythonFunctionDefinition(name, new PythonBlock(body));
+    }
+    
+    String name;
+    PythonBlock body;
+    
+    @Override
+    public <T> T accept(PythonNodeVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonIntegerLiteralNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonIntegerLiteralNode.java
new file mode 100644
index 0000000..d8a9358
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonIntegerLiteralNode.java
@@ -0,0 +1,15 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+import lombok.Value;
+
+@Value(staticConstructor="pythonIntegerLiteral")
+public class PythonIntegerLiteralNode implements PythonExpressionNode {
+    int value;
+
+    @Override
+    public <T> T accept(PythonNodeVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonModuleNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonModuleNode.java
new file mode 100644
index 0000000..92d63a8
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonModuleNode.java
@@ -0,0 +1,18 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import java.util.List;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+import lombok.Value;
+
+@Value(staticConstructor="pythonModule")
+public class PythonModuleNode implements PythonNode {
+    List<PythonStatementNode> statements;
+    
+    @Override
+    public <T> T accept(PythonNodeVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonNode.java
new file mode 100644
index 0000000..cdda65d
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonNode.java
@@ -0,0 +1,7 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+public interface PythonNode {
+    <T> T accept(PythonNodeVisitor<T> visitor);
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonPassNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonPassNode.java
new file mode 100644
index 0000000..36d6695
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonPassNode.java
@@ -0,0 +1,16 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+public class PythonPassNode implements PythonStatementNode {
+    public static final PythonPassNode PASS = new PythonPassNode();
+    
+    private PythonPassNode() {
+        // TODO Auto-generated constructor stub
+    }
+    
+    @Override
+    public <T> T accept(PythonNodeVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonReturnNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonReturnNode.java
new file mode 100644
index 0000000..b204b4d
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonReturnNode.java
@@ -0,0 +1,16 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+import lombok.Value;
+
+@Value(staticConstructor="pythonReturn")
+public class PythonReturnNode implements PythonStatementNode {
+    PythonExpressionNode value;
+    
+    @Override
+    public <T> T accept(PythonNodeVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+    
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonStatementNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonStatementNode.java
new file mode 100644
index 0000000..c27a7dd
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonStatementNode.java
@@ -0,0 +1,5 @@
+package org.zwobble.couscous.backends.python.ast;
+
+public interface PythonStatementNode extends PythonNode {
+
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonStringLiteralNode.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonStringLiteralNode.java
new file mode 100644
index 0000000..82d91db
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonStringLiteralNode.java
@@ -0,0 +1,15 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import org.zwobble.couscous.backends.python.ast.visitors.PythonNodeVisitor;
+
+import lombok.Value;
+
+@Value(staticConstructor="pythonStringLiteral")
+public class PythonStringLiteralNode implements PythonExpressionNode {
+    String value;
+    
+    @Override
+    public <T> T accept(PythonNodeVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/PythonWriter.java b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonWriter.java
new file mode 100644
index 0000000..4ab04c6
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/PythonWriter.java
@@ -0,0 +1,60 @@
+package org.zwobble.couscous.backends.python.ast;
+
+import com.google.common.base.Strings;
+
+public class PythonWriter {
+    private static final int SPACES_PER_INDENT = 4;
+    private final StringBuilder builder = new StringBuilder();
+    private int depth = 0;
+    
+    public String asString() {
+        return builder.toString();
+    }
+
+    public void writeInteger(int value) {
+        builder.append(value);
+    }
+
+    public void writeStringLiteral(String value) {
+        builder.append("\"");
+        builder.append(value);
+        builder.append("\"");
+    }
+
+    public void writeKeyword(String keyword) {
+        builder.append(keyword);
+    }
+
+    public void writeSpace() {
+        builder.append(" ");
+    }
+
+    public void writeIdentifier(String name) {
+        builder.append(name);
+    }
+
+    public void writeSymbol(String symbol) {
+        builder.append(symbol);
+    }
+
+    public void startBlock() {
+        depth++;
+        writeSymbol(":");
+        builder.append("\n");
+    }
+
+    public void endBlock() {
+        depth--;
+    }
+
+    public void startStatement() {
+        builder.append(Strings.repeat(" ", depth * SPACES_PER_INDENT));
+    }
+
+    public void endStatement() {
+        if (builder.charAt(builder.length() - 1) != '\n') {
+            builder.append("\n");   
+        }
+    }
+
+}
diff --git a/src/main/java/org/zwobble/couscous/backends/python/ast/visitors/PythonNodeVisitor.java b/src/main/java/org/zwobble/couscous/backends/python/ast/visitors/PythonNodeVisitor.java
new file mode 100644
index 0000000..0210df6
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/backends/python/ast/visitors/PythonNodeVisitor.java
@@ -0,0 +1,22 @@
+package org.zwobble.couscous.backends.python.ast.visitors;
+
+import org.zwobble.couscous.backends.python.ast.PythonClassNode;
+import org.zwobble.couscous.backends.python.ast.PythonFunctionDefinitionNode;
+import org.zwobble.couscous.backends.python.ast.PythonIntegerLiteralNode;
+import org.zwobble.couscous.backends.python.ast.PythonModuleNode;
+import org.zwobble.couscous.backends.python.ast.PythonPassNode;
+import org.zwobble.couscous.backends.python.ast.PythonReturnNode;
+import org.zwobble.couscous.backends.python.ast.PythonStringLiteralNode;
+
+public interface PythonNodeVisitor<T> {
+    T visit(PythonIntegerLiteralNode integerLiteral);
+    T visit(PythonStringLiteralNode stringLiteral);
+    
+    T visit(PythonReturnNode pythonReturn);
+    T visit(PythonPassNode pass);
+    T visit(PythonClassNode pythonClass);
+    T visit(PythonFunctionDefinitionNode functionDefinition);
+
+    T visit(PythonModuleNode module);
+
+}