start making errors a bit nicer

1 files changed, 48 insertions, 9 deletions

diff --git a/compiler.d b/compiler.d
index 992e36b..eccc4ce 100644
--- a/compiler.d
+++ b/compiler.d
@@ -18,6 +18,15 @@ struct TC {
     OpCode op;
 }
 
+struct CompileError {
+    string message;
+    int line;
+}
+
+string printableCompilerError(CompileError err) {
+    return format("[line %d] %s", err.line, err.message);
+}
+
 class Compiler {
 
     Function func;
@@ -30,6 +39,8 @@ class Compiler {
 
     int currentLine;
 
+    CompileError[] errors;
+
     Form outer;
     int outerIdx;
 
@@ -45,6 +56,11 @@ class Compiler {
         this.current = this.parser.parseForm();
     }
 
+    void error(string message, int line) {
+        CompileError err = { message, line };
+        this.errors ~= err;
+    }
+
     void compileNil(Form form) {
         form.compile(this.func);
         this.advance();
@@ -227,7 +243,10 @@ class Compiler {
     //ValueType compileLess(Form[] args, ValueType expected = ValueType.ANY) {
     ValueType compileLess(Form[] args, ValueType expected) {
         if (args.length != 2) {
+            /*
             writeln("'<' requires 2 arguments");
+            */
+            this.error("'<' requires 2 arguments", -1);
             this.advance();
             return ValueType.NIL;
         }
@@ -266,8 +285,11 @@ class Compiler {
 
     ValueType compileGreater(Form[] args) {
         if (args.length != 2) {
-            writeln("'>' requires 2 arguments");
+            this.error("'>' requires 2 arguments", -1);
             this.advance();
+            /*
+            writeln("'>' requires 2 arguments");
+            */
             return ValueType.NIL;
         }
         ValueType vt1 = this.resolve(args[0], ValueType.NUMBER);
@@ -316,7 +338,8 @@ class Compiler {
             }
 
             if (sym.name == local.sym.name) {
-                writefln("ERROR: already a variable named '%s' in this scope", sym.name);
+                this.error(format("already a variable named '%s' in this scope", sym.name), sym.line);
+                //writefln("ERROR: already a variable named '%s' in this scope", sym.name);
                 return;
             }
         }
@@ -356,12 +379,9 @@ class Compiler {
     */
 
     int resolveLocal(Symbol sym) { 
-        writefln("resolving local: %s", sym.name);
         for (int i = this.localCount - 1; i >= 0; i--) {
             Local local = this.locals[i];
-            writefln(" > [%d] %s (%s)", i, local.sym.name, local.depth);
             if (local.sym.name == sym.name) {
-                writeln("got it!");
                 return i;
             }
         }
@@ -535,7 +555,9 @@ class Compiler {
     void compileLength(Form[] args) {
         // TODO how do we identify/propagate errors?
         if (args.length != 1) {
-            writeln("COMPILE ERROR: 'first' expects exactly one argument");
+            this.error("'length': expected [1] argument, received 0", -1);
+            //writeln("COMPILE ERROR: 'first' expects exactly one argument");
+            this.advance();
             return;
         }
         ValueType vt = this.resolve(args[0], ValueType.SEQ); // TODO need a new type
@@ -563,7 +585,9 @@ class Compiler {
     void compileFirst(Form[] args) {
         // TODO how do we identify/propagate errors?
         if (args.length != 1) {
-            writeln("COMPILE ERROR: 'first' expects exactly one argument");
+            this.error("'first': expected [1] argument, received 0", -1);
+            this.advance();
+            //writeln("COMPILE ERROR: 'first' expects exactly one argument");
             return;
         }
         ValueType vt = this.resolve(args[0], ValueType.SEQ); // TODO need a new type
@@ -580,7 +604,9 @@ class Compiler {
     void compileRest(Form[] args) {
         // TODO how do we identify/propagate errors?
         if (args.length != 1) {
-            writeln("COMPILE ERROR: 'first' expects exactly one argument");
+            this.error("'rest': expected [1] argument, received ?", -1);
+            this.advance();
+            //writeln("COMPILE ERROR: 'first' expects exactly one argument");
             return;
         }
         ValueType vt = this.resolve(args[0], ValueType.OBJ); // TODO need a new type
@@ -622,6 +648,11 @@ class Compiler {
         this.func.chunk.writeOp(OpCode.OP_CONSTANT, lamb.line);
         int funcAddr = this.func.chunk.addConstant(makeObjValue(outFunc));
         this.func.chunk.writeOp(to!ubyte(funcAddr), lamb.line);
+
+        // capture the errors
+        foreach (CompileError err ; compiler.errors) {
+            this.errors ~= err;
+        }
     }
 
     void compileFunc(Form form) {
@@ -657,6 +688,11 @@ class Compiler {
         int funcAddr = this.func.chunk.addConstant(makeObjValue(outFunc));
         this.func.chunk.writeOp(to!ubyte(funcAddr), f.line);
 
+        // capture the errors
+        foreach (CompileError err ; compiler.errors) {
+            this.errors ~= err;
+        }
+
         // define the global variable
         this.defineVariable(global);
     }
@@ -673,7 +709,7 @@ class Compiler {
         }
 
         if (head.type != FormType.SYMBOL) {
-            writeln("cons must start with a symbol");
+            this.error("can't evaluate without a symbol or lambda", head.line);
             this.advance();
             return ValueType.NIL;
         }
@@ -712,6 +748,9 @@ class Compiler {
                 return this.compileConcat(cons.tail);
 
             // LISTS
+            case "append":
+                this.compileAppend(cons.tail);
+                break;
             case "first":
                 this.compileFirst(cons.tail);
                 break;