Switch Codegen

Author: vltir

src/main/java/com/compiler/ast/ASTCaseListNode.java

@@ -17,11 +17,6 @@ public void execute(OutputStreamWriter out) {
         m_caseList.forEach(caseItem->caseItem.execute(out));
     }
 
-    @Override
-    public void codegen(CompileEnvIntf env) {
-        m_caseList.forEach(caseItem->caseItem.codegen(env));
-    }
-
     @Override
     public void print(OutputStreamWriter outStream, String indent) throws Exception {
         outStream.write(indent);

src/main/java/com/compiler/ast/ASTCaseNode.java

@@ -1,5 +1,7 @@
 package com.compiler.ast;
 
+import com.compiler.CompileEnvIntf;
+
 import java.io.OutputStreamWriter;
 
 public class ASTCaseNode extends ASTStmtNode {

src/main/java/com/compiler/ast/ASTSwitchStmtNode.java

@@ -1,6 +1,11 @@
 package com.compiler.ast;
 
+import com.compiler.*;
+import com.compiler.instr.*;
+
 import java.io.OutputStreamWriter;
+import java.util.ArrayList;
+import java.util.List;
 
 public class ASTSwitchStmtNode extends ASTStmtNode {
 
@@ -21,6 +26,63 @@ public void execute(OutputStreamWriter out) {
         m_caseList.execute(out);
     }
 
+    @Override
+    public void codegen(CompileEnvIntf env) {
+        InstrBlock headBlock = env.createBlock(env.createUniqueSymbol("Switch_Head").m_name);
+        env.addInstr(new InstrJump(headBlock));
+        env.setCurrentBlock(headBlock);
+        InstrBlock exitBlock = env.createBlock(env.createUniqueSymbol("Switch_Exit").m_name);
+
+        if(m_caseList.m_caseList.isEmpty()){
+            env.addInstr(new InstrJump(exitBlock));
+            env.setCurrentBlock(exitBlock);
+            return;
+        }
+
+        InstrIntf switchExpression = m_expression.codegen(env);
+        Symbol switchExpressionSymbol = env.createUniqueSymbol("switch");
+        InstrIntf assignSwitchExpression = new InstrAssign(switchExpressionSymbol, switchExpression);
+        env.addInstr(assignSwitchExpression);
+
+        //Body Block Loop
+        List<InstrBlock> bodyBlocks = new ArrayList<>();
+        for (int i = 0; i < m_caseList.m_caseList.size(); i++) {
+            InstrBlock bodyBlock = env.createBlock(env.createUniqueSymbol("CaseExecute" + i).m_name);
+            bodyBlocks.add(bodyBlock);
+            env.setCurrentBlock(bodyBlock);
+            m_caseList.m_caseList.get(i).m_stmtList.codegen(env);
+            env.addInstr(new InstrJump(exitBlock));
+        }
+
+        //Check Block Loop
+        List<InstrBlock> checkBlocks = new ArrayList<>();
+        List<InstrIntf> equalInstrs =  new ArrayList<>();
+        for (int i = 0; i < m_caseList.m_caseList.size(); i++) {
+            InstrBlock caseBlock = env.createBlock(env.createUniqueSymbol("CaseCheck" + i).m_name);
+            checkBlocks.add(caseBlock);
+            env.setCurrentBlock(caseBlock);
+            InstrIntf switchValue = new InstrVariableExpr(switchExpressionSymbol);
+            env.addInstr(switchValue);
+            InstrIntf caseLiteral = m_caseList.m_caseList.get(i).m_value.codegen(env);
+            InstrIntf equals = new InstrCompare(TokenIntf.Type.EQUAL, switchValue, caseLiteral);
+            equalInstrs.add(equals);
+            env.addInstr(equals);
+        }
+
+        for (int i = 0; i < checkBlocks.size() - 1; i++) {
+            env.setCurrentBlock(checkBlocks.get(i));
+            env.addInstr(new InstrCondJump(equalInstrs.get(i), bodyBlocks.get(i), checkBlocks.get(i+1)));
+        }
+
+        env.setCurrentBlock(checkBlocks.get(checkBlocks.size()-1));
+        env.addInstr(new InstrCondJump(equalInstrs.get(checkBlocks.size()-1), bodyBlocks.get(checkBlocks.size()-1), exitBlock));
+
+        env.setCurrentBlock(headBlock);
+        env.addInstr(new InstrJump(checkBlocks.get(0)));
+
+        env.setCurrentBlock(exitBlock);
+    }
+
     @Override
     public void print(OutputStreamWriter outStream, String indent) throws Exception {
         outStream.write(indent);

src/test/java/com/compiler/InterpreterSwitchStmtTest.java

@@ -76,6 +76,6 @@ public void testSwitchProgram03() throws Exception {
                     PRINT out;
                 }
                 """;
-        testInterpreter(program, "5\n");
+        testInterpreter(program, "4\n3\n");
     }
 }