if/else, 'and' control flow

1 files changed, 85 insertions, 9 deletions

diff --git a/parser.d b/parser.d
index 80e1626..3dd32ef 100644
--- a/parser.d
+++ b/parser.d
@@ -14,6 +14,8 @@ enum FormType {
     FUNC,
     DEF,
     BLOCK,
+    IF,
+    AND,
 
     EOF,
     PARSE_ERROR
@@ -134,6 +136,46 @@ class Cons : Form {
     }
 }
 
+class If : Form {
+
+    Form cond;
+    Form thenForm;
+    Form elseForm;
+    bool hasElse;
+
+    this(int line, Form cond, Form then) {
+        this.line = line;
+        this.type = FormType.IF;
+        this.cond = cond;
+        this.thenForm = then;
+        this.hasElse = false;
+    }
+
+    this(int line, Form cond, Form then, Form else_) {
+        this.line = line;
+        this.type = FormType.IF;
+        this.cond = cond;
+        this.thenForm = then;
+        this.elseForm = else_;
+        this.hasElse = true;
+    }
+
+}
+
+class And : Form {
+
+    Form[] clauses;
+
+    this(int line) {
+        this.line = line;
+        this.type = FormType.AND;
+    }
+
+    void addClause(Form clause) {
+        clauses ~= clause;
+    }
+}
+
 class Func : Form {
 
     Symbol name;
@@ -252,7 +294,6 @@ class Parser {
     int line;
 
     bool peekable() {
-        writefln("pos %d source %d", pos, source.length);
         return (pos < source.length);
     }
 
@@ -260,14 +301,14 @@ class Parser {
         if (pos < source.length) {
             return source[pos];
         } else {
-            writeln("peek returns null");
+            //writeln("peek returns null");
             return '\0';
         }
     }
 
     char advance() {
         if (!peekable()) {
-            writeln("trying to advance() beyond the end!!!");
+            //writeln("trying to advance() beyond the end!!!");
             return '\0';
         } else {
             char ret = peek();
@@ -288,7 +329,6 @@ class Parser {
             if (peek() == '\n') {
                 line++;
             }
-            //pos++;
             advance();
         }
     }
@@ -365,8 +405,6 @@ class Parser {
 
         advance();  // closing paren
 
-        writefln("ending DEF pos %d", pos);
-
         return def;
     }
 
@@ -405,6 +443,43 @@ class Parser {
         return func;
     }
 
+    Form parseIf() {
+        If if_;
+        Form cond = parseForm();
+        Form then = parseForm();
+        if(peekable() && peek() == ')') {
+            if_ = new If(cond.line, cond, then);
+        } else {
+            Form else_ = parseForm();
+            if_ = new If(cond.line, cond, then, else_);
+        }
+
+        advance();  // consume closing paren
+
+        return if_;
+    }
+
+    Form parseAnd() {
+        And and_ = new And(line);
+        char next;
+        while(peekable()) {
+            next = peek();
+            if (next == ')') {
+                break;
+            }
+            and_.addClause(parseForm());
+        }
+
+        if (!peekable()) {
+            return new ParseError("unterminated and", line);
+        }
+
+        advance();  // consume closing paren
+
+        return and_;
+
+    }
+
     Form parseBlock() {
         Block block = new Block(line);
         char next;
@@ -420,7 +495,6 @@ class Parser {
             return new ParseError("unterminated block", line);
         }
 
-        writefln("ending block pos %d", pos);
         advance();  // consume closing paren
 
         return block;
@@ -448,6 +522,10 @@ class Parser {
                     return parseDef();
                 case "block":
                     return parseBlock();
+                case "if":
+                    return parseIf();
+                case "and":
+                    return parseAnd();
                 default:
                     break;
             }
@@ -496,8 +574,6 @@ class Parser {
                 return parseSymbol();
         }
 
-        writeln("FELL THROUGH ON PARSE FORM");
-
         advance();
 
         return new Atom(0, -1);