if/else, 'and' control flow

1 files changed, 67 insertions, 49 deletions

diff --git a/compiler.d b/compiler.d
index a7a5bfa..c05aeaa 100644
--- a/compiler.d
+++ b/compiler.d
@@ -92,13 +92,9 @@ class Compiler {
 
     int parseVariable(Def def) {
 
-        writefln("in parseVariable(), scopeDepth is %d", scopeDepth);
-
         declareVariable(def.name);
         if (scopeDepth > 0) {
             return 0;
-            //return localCount - 1;
-            //return localCount;
         }
 
         int addr = func.chunk.addConstant(makeStringValue(def.name.name));
@@ -131,7 +127,6 @@ class Compiler {
             }
         }
 
-        writefln("> > > creating a local '%s' at %d", sym.name, scopeDepth);
         Local loc = Local(sym, scopeDepth);
         if (localCount == locals.length) {
             locals ~= loc;
@@ -139,7 +134,6 @@ class Compiler {
             locals[localCount] = loc;
         }
         localCount++;
-        writefln("localcount is now %d", localCount);
     }
 
     void compileDef(Form form) {
@@ -153,27 +147,16 @@ class Compiler {
 
         // are we setting a local?
         if (scopeDepth > 0) {
-            //func.chunk.writeOp(OpCode.OP_SET_LOCAL, current.line);
             func.chunk.writeOp(OpCode.OP_DEF_LOCAL, current.line);
-            //func.chunk.writeOp(to!ubyte(addr), current.line);
         }
 
         // define the variable
         defineVariable(addr);
-        /*
-        func.chunk.writeOp(OpCode.OP_DEFINE_GLOBAL, current.line);
-        func.chunk.writeOp(to!ubyte(addr), current.line);
-        */
-
-        // is this right?
-        //func.chunk.writeOp(OpCode.OP_POP, def.line);
     }
 
     int resolveLocal(Symbol sym) { 
-        //for (int i = localCount - 1; i >= 0; i--) {
         for (int i = localCount - 1; i >= 0; i--) {
             Local local = locals[i];
-            writefln(" > > looping, looking at '%s' (%d) (depth: %d) (resolving: %s)", local.sym.name, i, local.depth, sym.name);
             if (local.sym.name == sym.name) {
                 return i;
             }
@@ -185,32 +168,80 @@ class Compiler {
     void compileSymbol(Form form) {
         Symbol sym = cast(Symbol)form;
 
-        //OpCode getOp;
-        //OpCode setOp;
         int arg = resolveLocal(sym);
         if (arg != -1) {
-            writeln("compiling a LOCAL symbol");
-            //getOp = OpCode.OP_GET_LOCAL;
             func.chunk.writeOp(OpCode.OP_GET_LOCAL, sym.line);
-            //setOp = OpCode.OP_SET_LOCAL; // do we need this here
         } else {
-            writeln("compiling a GLOBAL symbol");
             arg = func.chunk.addConstant(makeStringValue(sym.name));
-            //getOp = OpCode.OP_GET_GLOBAL;
             func.chunk.writeOp(OpCode.OP_GET_GLOBAL, sym.line);
-            //setOp = OpCode.OP_SET_GLOBAL; // do we need this here
         }
 
-        // add the symbol name to the chunk
-        //int addr = func.chunk.addConstant(makeStringValue(sym.name));
-
         // get the variable
-        //func.chunk.writeOp(getOp, sym.line);
         func.chunk.writeOp(to!ubyte(arg), sym.line);
 
         //advance();
     }
 
+    int jump(OpCode type) {
+        func.chunk.writeOp(to!ubyte(type), current.line);
+        func.chunk.writeOp(0xff, current.line);
+        func.chunk.writeOp(0xff, current.line);
+        return to!int(func.chunk.code.length) - 2;
+    }
+
+    void patchJump(int offset) {
+        // additional -2 to account for the 2 byte jump itself
+        int jmp = to!int(func.chunk.code.length) - offset - 2;
+
+        // TODO check to make sure we didn't jump too far?
+
+        this.func.chunk.code[offset] = (jmp >> 8) & 0xff;
+        this.func.chunk.code[offset + 1] = jmp & 0xff;
+    }
+
+    void compileIf(Form form) {
+        If if_ = cast(If)form;
+
+        resolve(if_.cond);
+
+        int thenJump = jump(OpCode.OP_JUMP_IF_FALSE);
+        this.func.chunk.writeOp(OpCode.OP_POP, if_.line);
+
+        resolve(if_.thenForm);
+
+        int elseJump = jump(OpCode.OP_JUMP);
+
+        patchJump(thenJump);
+        this.func.chunk.writeOp(OpCode.OP_POP, if_.line);
+
+        if (if_.hasElse) {
+            resolve(if_.elseForm);
+        }
+
+        patchJump(elseJump);
+
+    }
+
+    void compileAnd(Form form) {
+        And and_ = cast(And)form;
+
+        resolve(and_.clauses[0]);
+        int[] jumps;
+        jumps ~= jump(OpCode.OP_JUMP_IF_FALSE);
+        int count = 1;
+        while (count < and_.clauses.length) {
+            this.func.chunk.writeOp(OpCode.OP_POP, and_.line);
+            resolve(and_.clauses[count]);
+            jumps ~= jump(OpCode.OP_JUMP_IF_FALSE);
+            count++;
+        }
+
+        // patch all the jumps
+        foreach (int jmp; jumps) {
+            patchJump(jmp);
+        }
+    }
+
     void compileBlock(Form form) {
         Block block = cast(Block)form;
         beginScope();
@@ -226,14 +257,10 @@ class Compiler {
 
     void endScope() {
 
-        writefln("> > ending scope at depth %d", scopeDepth);
         scopeDepth--;
 
         while (localCount > 0 &&
                 locals[localCount - 1].depth > scopeDepth) {
-            writeln("> > looping, gonna pop");
-            //func.chunk.writeOp(to!ubyte(OpCode.OP_POP_SCOPE), -1);
-            //func.chunk.writeOp(to!ubyte(OpCode.OP_POP), -1);
             func.chunk.writeOp(OpCode.OP_POPB, -1);
             localCount--;
         }
@@ -274,8 +301,7 @@ class Compiler {
     }
 
     void resolve(Form form) {
-        write("resolving: ");
-        printForm(form);
+        //printForm(form);
         switch(form.type) {
             case FormType.ATOM:
                 this.compileAtom(form);
@@ -288,15 +314,19 @@ class Compiler {
                 break;
             case FormType.DEF:
                 this.compileDef(form);
-                writeln("DONE COMPILING DEF");
                 break;
             case FormType.SYMBOL:
                 this.compileSymbol(form);
                 break;
             case FormType.BLOCK:
-                writeln("COMPILING BLOCK");
                 this.compileBlock(form);
                 break;
+            case FormType.IF:
+                this.compileIf(form);
+                break;
+            case FormType.AND:
+                this.compileAnd(form);
+                break;
             default:
                 write("not sure how to resolve: ");
                 printForm(form);
@@ -306,28 +336,16 @@ class Compiler {
     }
 
     Function compile() {
-        writeln("compiling");
         advance();
         while(current.type != FormType.EOF) {
-            writeln("IN COMPILE LOOP");
             resolve(current);
-            writeln("BOTTOM OF COMPILE LOOP");
-            if (current.type == FormType.EOF) {
-                writeln("got an EOF");
-            }
         }
         
-        writeln("outside compile loop");
-        
         return finish();
     }
 
     Function finish() {
-        //emitReturn();
-        writeln("finishing the compiler!");
-
         this.func.chunk.writeOp(OpCode.OP_RETURN, current.line);
-        writeln("wrote a return code");
         return func;
     }