Update the lexer, parser and AST to match the language definition.

Add toString() method on AST nodes so that we can easily check the results of parsing.
Remove AA lexer
Move the Ecstasy lexer classes to one package, except Handy

14 files changed, 258 insertions, 347 deletions

diff --git a/chapter01/src/main/java/com/seaofnodes/simple/parser/Ast.java b/chapter01/src/main/java/com/seaofnodes/simple/parser/Ast.java
index a93b230f..b11d1ddb 100644
--- a/chapter01/src/main/java/com/seaofnodes/simple/parser/Ast.java
+++ b/chapter01/src/main/java/com/seaofnodes/simple/parser/Ast.java
@@ -1,48 +1,94 @@
+/*
+ * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ * <p>
+ * Contributor(s):
+ * <p>
+ * The Initial Developer of the Original Software is Dibyendu Majumdar.
+ * <p>
+ * This file is part of the Sea Of Nodes Simple Programming language
+ * implementation. See https://github.com/SeaOfNodes/Simple
+ * <p>
+ * The contents of this file are subject to the terms of the
+ * Apache License Version 2 (the "APL"). You may not use this
+ * file except in compliance with the License. A copy of the
+ * APL may be obtained from:
+ * http://www.apache.org/licenses/LICENSE-2.0
+ */
 package com.seaofnodes.simple.parser;
 
-import com.seaofnodes.simple.common.CompilerException;
 import com.seaofnodes.simple.lexer.ecstasy.Token;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
-public abstract class Ast {
+/**
+ * A simple AST definition.
+ */
+public class Ast {
 
-    public static class Node {
+    private Ast() {
     }
 
-    public static class Expr extends Node {
+    public interface Node {
+    }
+
+    public abstract static class Expr implements Node {
         public final Token op;
 
-        public Expr(Token op) {
+        protected Expr(Token op) {
             this.op = op;
         }
     }
 
+    /**
+     * A name in the language
+     */
     public static class Identifier extends Expr {
         public final String name;
+
         public Identifier(Token op) {
             super(op);
             name = op.getValueText();
         }
+
+        @Override
+        public String toString() {
+            return name;
+        }
     }
 
+    /**
+     * Reference to a name in the language
+     */
     public static class Symbol extends Expr {
         public final String name;
+
         public Symbol(Token op) {
             super(op);
             name = op.getValueText();
         }
+
+        @Override
+        public String toString() {
+            return name;
+        }
     }
 
     public static class Binary extends Expr {
-        public final Expr expr1, expr2;
+        public final Expr expr1;
+        public final Expr expr2;
 
         public Binary(Token op, Expr expr1, Expr expr2) {
             super(op);
             this.expr1 = expr1;
             this.expr2 = expr2;
         }
+
+        @Override
+        public String toString() {
+            return "(" + expr1 + op.getValueText() + expr2 + ")";
+        }
     }
 
     public static class Unary extends Expr {
@@ -52,49 +98,65 @@ public abstract class Ast {
             super(op);
             this.expr = expr;
         }
+
+        @Override
+        public String toString() {
+            return "(" + op.getValueText() + "(" + expr + "))";
+        }
     }
 
     public static class Constant extends Expr {
         public Constant(Token op) {
             super(op);
         }
+
+        @Override
+        public String toString() {
+            return op.getValueText();
+        }
     }
 
-    public static class Statement extends Node {
+    public abstract static class Statement implements Node {
     }
 
     public static class IfElse extends Statement {
         public final Expr expr;
-        public final Statement ifStmt, elseStmt;
+        public final Statement ifStmt;
+        public final Statement elseStmt;
 
         public IfElse(Expr expr, Statement ifStmt, Statement elseStmt) {
             this.expr = expr;
             this.ifStmt = ifStmt;
             this.elseStmt = elseStmt;
         }
+
+        @Override
+        public String toString() {
+            if (elseStmt != null)
+                return "if(" + expr + ") " + ifStmt + " else " + elseStmt;
+            return "if(" + expr + ") " + ifStmt;
+        }
     }
 
     public static class While extends Statement {
-        public Expr expr;
-        public Statement stmt;
+        public final Expr expr;
+        public final Statement stmt;
 
-        public While() {
-        }
-        public void init(Expr expr, Statement stmt) {
+        public While(Expr expr, Statement stmt) {
             this.expr = expr;
             this.stmt = stmt;
         }
+
+        @Override
+        public String toString() {
+            return "while(" + expr.toString() + ") " + stmt;
+        }
     }
 
     public static class Break extends Statement {
-        public final Statement stmt;
-
-        public Break(Statement stmt) {
-            if (stmt == null)
-            {
-                throw new CompilerException("uneclosed break");
-            }
-            this.stmt = stmt;
+        @Override
+        public String toString() {
+            return "break;";
         }
     }
 
@@ -106,14 +168,24 @@ public abstract class Ast {
             this.identifier = identifier;
             this.expr = expr;
         }
+
+        @Override
+        public String toString() {
+            return identifier.toString() + "=" + expr.toString() + ";";
+        }
     }
 
-    public static class Type extends Node {
+    public static class Type implements Node {
         public final Token.Id typeId;
 
         public Type(Token.Id typeId) {
             this.typeId = typeId;
         }
+
+        @Override
+        public String toString() {
+            return typeId.TEXT;
+        }
     }
 
     public static class Declare extends Statement {
@@ -124,9 +196,20 @@ public abstract class Ast {
             this.type = type;
             this.identifier = identifier;
         }
+
+        @Override
+        public String toString() {
+            return type.toString() + " " + identifier.toString() + ";";
+        }
     }
 
     public static class Block extends Statement {
         public final List<Statement> stmtList = new ArrayList<>();
+
+        @Override
+        public String toString() {
+            return "{" +
+                    stmtList.stream().map(Object::toString).collect(Collectors.joining()) + "}";
+        }
     }
 }
diff --git a/chapter01/src/main/java/com/seaofnodes/simple/parser/Parser.java b/chapter01/src/main/java/com/seaofnodes/simple/parser/Parser.java
index b36942d4..263d0b41 100644
--- a/chapter01/src/main/java/com/seaofnodes/simple/parser/Parser.java
+++ b/chapter01/src/main/java/com/seaofnodes/simple/parser/Parser.java
@@ -1,4 +1,4 @@
-/**
+/*
  * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
  *
  * Contributor(s):
@@ -16,28 +16,28 @@
  */
 package com.seaofnodes.simple.parser;
 
-import com.seaofnodes.simple.common.CompilerException;
+import com.seaofnodes.simple.lexer.ecstasy.CompilerException;
 import com.seaofnodes.simple.lexer.ecstasy.Lexer;
 import com.seaofnodes.simple.lexer.ecstasy.Token;
-import com.seaofnodes.simple.common.Severity;
+import com.seaofnodes.simple.lexer.ecstasy.Severity;
 
 public class Parser {
     final Lexer lexer;
     Token look;
-    Ast.Statement statementEnclosing;
 
     public Parser(Lexer lexer) {
         this.lexer = lexer;
     }
 
-    Token nextOrEof() {
+    private Token nextOrEof() {
         if (lexer.hasNext())
             return lexer.next();
         return new Token(look.getStartPosition(), look.getEndPosition(), Token.Id.EOF);
     }
 
-    void nextToken() {
+    private void nextToken() {
         look = nextOrEof();
+        // skip comments
         while (look.isComment()) {
             look = nextOrEof();
         }
@@ -47,12 +47,12 @@ public class Parser {
         }
     }
 
-    void error(Token t, String errorMessage) {
+    private void error(Token t, String errorMessage) {
         lexer.log(Severity.ERROR, errorMessage, t.getStartPosition(), t.getEndPosition());
         throw new CompilerException(errorMessage + ": " + t.toDebugString());
     }
 
-    void match(Token.Id tag) {
+    private void match(Token.Id tag) {
         if (look.getId() == tag) {
             nextToken();
         } else {
@@ -65,43 +65,40 @@ public class Parser {
         return parseProgram();
     }
 
-    Ast.Statement parseProgram() {
+    private Ast.Statement parseProgram() {
         var block = new Ast.Block();
         parseDeclarations(block);
         parseStatements(block);
         return block;
     }
 
-    void parseDeclarations(Ast.Block block) {
-        while (look.getId() == Token.Id.VAR) {
+    private boolean isTypeName(Token tok) {
+        return switch (tok.getId()) {
+            case TYPE_INT, TYPE_CHAR, TYPE_FLOAT -> true;
+            default -> false;
+        };
+    }
+
+    private void parseDeclarations(Ast.Block block) {
+        while (isTypeName(look)) {
+            var type = new Ast.Type(look.getId());
             nextToken();
             var tok = look;
             match(Token.Id.IDENTIFIER);
-            match(Token.Id.COLON);
-            var type = parseType();
             match(Token.Id.SEMICOLON);
             var identifier = new Ast.Identifier(tok);
             block.stmtList.add(new Ast.Declare(type, identifier));
         }
     }
 
-    Ast.Type parseType() {
-        if (look.getId() == Token.Id.LIT_INTA) {
-            nextToken();
-            return new Ast.Type(look.getId());
-        }
-        error(look, "syntax error: unsupported type (at present only Int type is allowed)");
-        return null;
-    }
-
-    void parseStatements(Ast.Block block) {
+    private void parseStatements(Ast.Block block) {
         while (look.getId() != Token.Id.EOF &&
                 look.getId() != Token.Id.R_CURLY) {
             block.stmtList.add(parseStatement());
         }
     }
 
-    Ast.Statement parseStatement() {
+    private Ast.Statement parseStatement() {
         Ast.Expr x;
         Ast.Statement s1;
         Ast.Statement s2;
@@ -120,22 +117,17 @@ public class Parser {
                 return new Ast.IfElse(x, s1, s2);
             }
             case WHILE -> {
-                var whilenode = new Ast.While();
-                var savedStmt = statementEnclosing;
-                statementEnclosing = whilenode;
                 match(Token.Id.WHILE);
                 match(Token.Id.L_PAREN);
                 x = parseBool();
                 match(Token.Id.R_PAREN);
                 s1 = parseStatement();
-                whilenode.init(x, s1);
-                statementEnclosing = savedStmt;
-                return whilenode;
+                return new Ast.While(x, s1);
             }
             case BREAK -> {
                 match(Token.Id.BREAK);
                 match(Token.Id.SEMICOLON);
-                return new Ast.Break(statementEnclosing);
+                return new Ast.Break();
             }
             case L_CURLY -> {
                 return parseBlock();
@@ -146,7 +138,7 @@ public class Parser {
         }
     }
 
-    Ast.Statement parseBlock() {
+    private Ast.Statement parseBlock() {
         match(Token.Id.L_CURLY);
         var block = new Ast.Block();
         parseDeclarations(block);
@@ -155,16 +147,17 @@ public class Parser {
         return block;
     }
 
-    Ast.Statement parseAssign() {
+    private Ast.Statement parseAssign() {
+        Token tok = look;
         match(Token.Id.IDENTIFIER);
-        Ast.Identifier identifier = new Ast.Identifier(look);
+        Ast.Identifier identifier = new Ast.Identifier(tok);
         match(Token.Id.ASN);
         var s = new Ast.Assign(identifier, parseBool());
         match(Token.Id.SEMICOLON);
         return s;
     }
 
-    Ast.Expr parseBool() {
+    private Ast.Expr parseBool() {
         var x = parseAnd();
         while (look.getId() == Token.Id.COND_OR) {
             var tok = look;
@@ -174,7 +167,7 @@ public class Parser {
         return x;
     }
 
-    Ast.Expr parseAnd() {
+    private Ast.Expr parseAnd() {
         var x = parseRelational();
         while (look.getId() == Token.Id.COND_AND) {
             var tok = look;
@@ -184,7 +177,7 @@ public class Parser {
         return x;
     }
 
-    Ast.Expr parseRelational() {
+    private Ast.Expr parseRelational() {
         var x = parseAddition();
         while (look.getId() == Token.Id.COMP_EQ ||
                 look.getId() == Token.Id.COMP_NEQ ||
@@ -199,7 +192,7 @@ public class Parser {
         return x;
     }
 
-    Ast.Expr parseAddition() {
+    private Ast.Expr parseAddition() {
         var x = parseMultiplication();
         while (look.getId() == Token.Id.ADD ||
                 look.getId() == Token.Id.SUB) {
@@ -210,7 +203,7 @@ public class Parser {
         return x;
     }
 
-    Ast.Expr parseMultiplication() {
+    private Ast.Expr parseMultiplication() {
         var x = parseUnary();
         while (look.getId() == Token.Id.MUL ||
                 look.getId() == Token.Id.DIV) {
@@ -221,7 +214,7 @@ public class Parser {
         return x;
     }
 
-    Ast.Expr parseUnary() {
+    private Ast.Expr parseUnary() {
         if (look.getId() == Token.Id.SUB ||
                 look.getId() == Token.Id.NOT) {
             var tok = look;
@@ -232,7 +225,7 @@ public class Parser {
         }
     }
 
-    Ast.Expr parsePrimary() {
+    private Ast.Expr parsePrimary() {
         switch (look.getId()) {
             case L_PAREN -> {
                 nextToken();
diff --git a/chapter01/src/test/java/com/seaofnodes/simple/lexer/TestParser.java b/chapter01/src/test/java/com/seaofnodes/simple/lexer/TestParser.java
index a89c1f6a..80917c0f 100644
--- a/chapter01/src/test/java/com/seaofnodes/simple/lexer/TestParser.java
+++ b/chapter01/src/test/java/com/seaofnodes/simple/lexer/TestParser.java
@@ -1,4 +1,4 @@
-/**
+/*
  * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
  *
  * Contributor(s):
@@ -15,10 +15,9 @@
 
 package com.seaofnodes.simple.lexer;
 
-import com.seaofnodes.simple.common.ErrorListener;
+import com.seaofnodes.simple.lexer.ecstasy.ErrorListener;
 import com.seaofnodes.simple.lexer.ecstasy.Lexer;
 import com.seaofnodes.simple.lexer.ecstasy.Source;
-import com.seaofnodes.simple.parser.Ast;
 import com.seaofnodes.simple.parser.Parser;
 import org.junit.Assert;
 import org.junit.Test;
@@ -28,30 +27,28 @@ public class TestParser {
     @Test
     public void testParseSingleDecl()
     {
-        final String source = "var i: Int;";
+        final String source = "int i;";
         Lexer lexer = new Lexer(new Source(source), new ErrorListener());
         Parser parser = new Parser(lexer);
         var ast = parser.parse();
-        Assert.assertTrue(ast instanceof Ast.Block
-            && ((Ast.Block) ast).stmtList.size() == 1);
+        Assert.assertEquals("{int i;}", ast.toString());
     }
 
     @Test
     public void testParseTwoDecls() {
-        final String source = "var i: Int;\nvar j: Int;";
+        final String source = "int i;\nint j;";
         Lexer lexer = new Lexer(new Source(source), new ErrorListener());
         Parser parser = new Parser(lexer);
         var ast = parser.parse();
-        Assert.assertTrue(ast instanceof Ast.Block
-                && ((Ast.Block) ast).stmtList.size() == 2);
+        Assert.assertEquals("{int i;int j;}", ast.toString());
     }
 
     @Test
     public void testIfAndWhile() {
         final String source =
                 """
-                var i: Int;
-                var j: Int;
+                int i;
+                int j;
                 
                 i = 0;
                 j = 100;
@@ -64,5 +61,6 @@ public class TestParser {
         Lexer lexer = new Lexer(new Source(source), new ErrorListener());
         Parser parser = new Parser(lexer);
         var ast = parser.parse();
+        Assert.assertEquals("{int i;int j;i=0;j=100;while(1) {i=(i+1);j=(j-1);if((i>=j)) break;}}", ast.toString());
     }
 }
diff --git a/common/src/main/java/com/seaofnodes/simple/common/CompilerException.java b/common/src/main/java/com/seaofnodes/simple/common/CompilerException.java
deleted file mode 100644
index 518dcde6..00000000
--- a/common/src/main/java/com/seaofnodes/simple/common/CompilerException.java
+++ /dev/null
@@ -1,11 +0,0 @@
-package com.seaofnodes.simple.common;
-
-public class CompilerException extends RuntimeException {
-    public CompilerException(String message) {
-        super(message);
-    }
-
-    public CompilerException(String message, Throwable cause) {
-        super(message, cause);
-    }
-}
diff --git a/common/src/main/java/com/seaofnodes/simple/common/Severity.java b/common/src/main/java/com/seaofnodes/simple/common/Severity.java
deleted file mode 100644
index f3325d52..00000000
--- a/common/src/main/java/com/seaofnodes/simple/common/Severity.java
+++ /dev/null
@@ -1,19 +0,0 @@
-package com.seaofnodes.simple.common;
-
-
-/**
- * Severity levels.
- */
-public enum Severity
-    {
-    NONE, INFO, WARNING, ERROR, FATAL;
-
-    public String desc()
-        {
-        String sName = name();
-        StringBuilder sb = new StringBuilder(sName.length());
-        sb.append(sName.charAt(0));
-        sb.append(sName.substring(1).toLowerCase());
-        return sb.toString();
-        }
-    }
diff --git a/common/src/main/java/com/seaofnodes/simple/lexer/aa/Lexer.java b/common/src/main/java/com/seaofnodes/simple/lexer/aa/Lexer.java
deleted file mode 100644
index 162cdea1..00000000
--- a/common/src/main/java/com/seaofnodes/simple/lexer/aa/Lexer.java
+++ /dev/null
@@ -1,228 +0,0 @@
-/**
- * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
- *
- * Contributor(s):
- *
- * The Initial Developer of the Original Software is Cliff Click.
- *
- * This file is part of the Sea Of Nodes Simple Programming language
- * implementation. See https://github.com/SeaOfNodes/Simple
- *
- * The contents of this file are subject to the terms of the
- * Apache License Version 2 (the "APL"). You may not use this
- * file except in compliance with the License. A copy of the
- * APL may be obtained from:
- * http://www.apache.org/licenses/LICENSE-2.0
- */
-package com.seaofnodes.simple.lexer.aa;
-
-import com.seaofnodes.util.AryInt;
-import com.seaofnodes.util.SB;
-
-import java.text.NumberFormat;
-import java.text.ParsePosition;
-
-public class Lexer {
-    private final String _srcName;    // Source for error messages; usually a file name
-    private final byte[] _buf;
-    private int _x;               // Parser index
-    private int _lastNWS;         // Index of last non-white-space char
-    private final AryInt _lines;  // char offset of each line
-
-    private final NumberFormat _nf;
-    private final ParsePosition _pp;
-    private final String _str;
-
-    public Lexer(String srcName, String source)
-    {
-        _srcName = srcName;
-        _buf = source.getBytes();
-        _x   = 0;
-
-        // Set fields strictly for Java number parsing
-        _nf = NumberFormat.getInstance();
-        _nf.setGroupingUsed(false);
-        _pp = new ParsePosition(0);
-        _str = source;           // Keep a complete string copy for java number parsing
-        _lines = new AryInt();//
-        _lines.push(0);       // Line 0 at offset 0
-    }
-
-    // Skip WS, return true&skip if match, false & do not skip if miss.
-    public boolean peek( char c ) { return peek1(skipWS(),c); }
-    public boolean peek_noWS( char c ) { return peek1(_x >= _buf.length ? -1 : _buf[_x],c); }
-    // Already skipped WS & have character;
-    // return true & skip if a match, false& do not skip if a miss.
-    public boolean peek1( byte c0, char c ) {
-        assert c0==-1 || c0== _buf[_x];
-        if( c0!=c ) return false;
-        _x++;                       // Skip peeked character
-        return true;
-    }
-    // Already skipped WS & have character;
-    // return true&skip if match, false & do not skip if miss.
-    public boolean peek2( byte c0, String s2 ) {
-        if( c0 != s2.charAt(0) ) return false;
-        if( _x+1 >= _buf.length || _buf[_x+1] != s2.charAt(1) ) return false;
-        _x+=2;                      // Skip peeked characters
-        return true;
-    }
-    public boolean peek( String s ) {
-        if( !peek(s.charAt(0)) ) return false;
-        if( !peek_noWS(s.charAt(1)) ) {  _x--; return false; }
-        return true;
-    }
-    // Peek 'c' and NOT followed by 'no'
-    public boolean peek_not( char c, char no ) {
-        byte c0 = skipWS();
-        if( c0 != c || (_x+1 < _buf.length && _buf[_x+1] == no) ) return false;
-        _x++;
-        return true;
-    }
-    // Match any of these, and return the match or null
-    public String peek(String[] toks) {
-        for( String tok : toks ) if( peek1(tok) ) return tok;
-        return null;
-    }
-    public boolean peek1(String tok) {
-        for( int i=0; i<tok.length(); i++ )
-            if( _x+i >= _buf.length || _buf[_x+i] != tok.charAt(i) )
-                return false;
-        return true;
-    }
-
-
-    /** Advance parse pointer to the first non-whitespace character, and return
-     *  that character, -1 otherwise.  */
-    public byte skipWS() {
-        int oldx = _x;
-        while( _x < _buf.length ) {
-            byte c = _buf[_x];
-            if( c=='/' && _x+1 < _buf.length && _buf[_x+1]=='/' ) { skipEOL()  ; continue; }
-            if( c=='/' && _x+1 < _buf.length && _buf[_x+1]=='*' ) { skipBlock(); continue; }
-            if( c=='\n' && _x+1 > _lines.last() ) _lines.push(_x+1);
-            if( !isWS(c) ) {
-                if( oldx-1 > _lastNWS && !isWS(_buf[oldx-1]) ) _lastNWS = oldx-1;
-                return c;
-            }
-            _x++;
-        }
-        return -1;
-    }
-    public void skipEOL  () { while( _x < _buf.length && _buf[_x] != '\n' ) _x++; }
-    public void skipBlock() { throw new UnsupportedOperationException("Block comments not yet implemented"); }
-    // Advance parse pointer to next WS.  Used for parser syntax error recovery.
-    public void skipNonWS() {
-        while( _x < _buf.length && !isWS(_buf[_x]) ) _x++;
-    }
-
-    /** Return true if `c` passes a test */
-    public static boolean isWS    (byte c) { return c == ' ' || c == '\t' || c == '\n' || c == '\r'; }
-    public static boolean isAlpha0(byte c) { return ('a'<=c && c <= 'z') || ('A'<=c && c <= 'Z') || (c=='_'); }
-    public static boolean isAlpha1(byte c) { return isAlpha0(c) || ('0'<=c && c <= '9'); }
-    public static boolean isJava  (byte c) { return isAlpha1(c) || (c=='$') || (c=='.'); }
-    public  static boolean isDigit (byte c) { return '0' <= c && c <= '9'; }
-
-    public String token() { skipWS();  return token0(); }
-    // Lexical tokens.  Any alpha, followed by any alphanumerics is a alpha-
-    // token; alpha-tokens end with WS or any operator character.  Any collection
-    // of the classic operator characters are a token, except that they will break
-    // un-ambiguously.
-    public String token0() {
-        if( _x >= _buf.length ) return null;
-        byte c=_buf[_x];  int x = _x;
-        if( isOp0(c) || (c=='_' && _x+1 < _buf.length && isOp0(_buf[_x+1])) )
-            while( _x < _buf.length && isOp1(_buf[_x]) ) _x++;
-        else if( isAlpha0(c) )
-            while( _x < _buf.length && isAlpha1(_buf[_x]) ) _x++;
-        else return null; // Not a token; specifically excludes e.g. all bytes >= 128, or most bytes < 32
-        if( (c==':' || c==',') && _x-x==1 ) // Disallow bare ':' as a token; ambiguous with ?: and type annotations; same for ','
-        { _x=x; return null; } // Unwind, not a token
-        if( c=='-' && _x-x>2 && _buf[x+1]=='>' ) // Disallow leading "->", confusing with function parameter list end; eg "not={x->!x}"
-            _x=x+2;                                // Just return the "->"
-        return new String(_buf,x,_x-x);
-    }
-    public boolean isOp(String s) {
-        if( s==null || s.isEmpty() ) return false;
-        byte c = (byte)s.charAt(0);
-        if( !isOp0(c) && (c!='_' || !isOp0((byte)s.charAt(1))) ) return false;
-        for( int i=1; i<s.length(); i++ )
-            if( !isOp1((byte)s.charAt(i)) ) return false;
-        return true;
-    }
-
-    // Parse a number; WS already skipped and sitting at a digit.  Relies on
-    // Javas number parsing.
-    public Number number() {
-        _pp.setIndex(_x);
-        Number n = _nf.parse(_str,_pp);
-        _x = _pp.getIndex();
-        if( n instanceof Long   ) {
-            if( _buf[_x-1]=='.' ) _x--; // Java default parser allows "1." as an integer; pushback the '.'
-        }
-        return n;
-    }
-
-    public int field_number() {
-        byte c = _buf[_x];
-        if( !isDigit(c) ) return -1;
-        _x++;
-        int sum = c-'0';
-        while( _x < _buf.length && isDigit(c=_buf[_x]) ) {
-            _x++;
-            sum = sum*10+c-'0';
-        }
-        return sum;
-    }
-
-    /** Parse a String; _x is at '"'.
-     *  str  = [.\%]*               // String contents; \t\n\r\% standard escapes
-     *  str  = %[num]?[.num]?fact   // Percent escape embeds a 'fact' in a string; "name=%name\n"
-     */
-    public String string() {
-        int oldx = ++_x;
-        byte c;
-        while( (c=_buf[_x++]) != '"' ) {
-            if( c=='%' ) throw new UnsupportedOperationException("Not implemented");
-            if( c=='\\' ) throw new UnsupportedOperationException("Not implemented");
-            if( _x == _buf.length ) return null;
-        }
-        return new String(_buf,oldx,_x-oldx-1).intern();
-    }
-
-    public static boolean isOp0(byte c) { return "!#$%*+-=<>^[]~/&|".indexOf(c) != -1; }
-    public static boolean isOp1(byte c) { return isOp0(c) || ":?_{}".indexOf(c) != -1; }
-
-    public String errLocMsg(String s) {
-        if( s.charAt(0)=='\n' ) return s;
-        // find line start
-        int a=_x;
-        while( a > 0 && _buf[a-1] != '\n' ) --a;
-        if( _buf[a]=='\r' ) a++; // do not include leading \n or \n\r
-        // find line end
-        int b=_x;
-        while( b < _buf.length && _buf[b] != '\n' ) b++;
-        if( b < _buf.length ) b--; // do not include trailing \n or \n\r
-        // Find line number.  Bin-search returns the insertion-point, which is the NEXT
-        // line unless _x is exactly a line start.
-        int line = _lines.binary_search(_x); // Find zero-based line insertion point
-        if( line == _lines._len ||  _lines.at(line)>_x ) line--;
-        // error message using 1-based line
-        SB sb = new SB().p(_srcName).p(':').p(line+1).p(':').p(s).nl();
-        sb.p(new String(_buf,a,b-a)).nl();
-        int line_start = a;
-        for( int i=line_start; i<_x; i++ )
-            sb.p(' ');
-        return sb.p('^').nl().toString();
-    }
-
-    @Override public String toString() { return new String(_buf,_x,_buf.length-_x); }
-    @Override public boolean equals(Object loc) {
-        if( this==loc ) return true;
-        if( !(loc instanceof Lexer p) ) return false;
-        return _x==p._x && _srcName.equals(p._srcName);
-    }
-    @Override public int hashCode() {
-        return _srcName.hashCode()+_x;
-    }
-}
diff --git a/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/CompilerException.java b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/CompilerException.java
new file mode 100644
index 00000000..c23d3672
--- /dev/null
+++ b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/CompilerException.java
@@ -0,0 +1,28 @@
+/*
+ * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Contributor(s):
+ *
+ * The Initial Developer of the Original Software is
+ * The Ecstasy Project (https://github.com/xtclang/).
+ *
+ * This file is part of the Sea Of Nodes Simple Programming language
+ * implementation. See https://github.com/SeaOfNodes/Simple
+ *
+ * The contents of this file are subject to the terms of the
+ * Apache License Version 2 (the "APL"). You may not use this
+ * file except in compliance with the License. A copy of the
+ * APL may be obtained from:
+ * http://www.apache.org/licenses/LICENSE-2.0
+ */
+package com.seaofnodes.simple.lexer.ecstasy;
+
+public class CompilerException extends RuntimeException {
+    public CompilerException(String message) {
+        super(message);
+    }
+
+    public CompilerException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}
diff --git a/common/src/main/java/com/seaofnodes/simple/common/ErrorListener.java b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/ErrorListener.java
index 29ca46b6..6a29f315 100644
--- a/common/src/main/java/com/seaofnodes/simple/common/ErrorListener.java
+++ b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/ErrorListener.java
@@ -1,11 +1,26 @@
-package com.seaofnodes.simple.common;
+/*
+ * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Contributor(s):
+ *
+ * The Initial Developer of the Original Software is
+ * The Ecstasy Project (https://github.com/xtclang/).
+ *
+ * This file is part of the Sea Of Nodes Simple Programming language
+ * implementation. See https://github.com/SeaOfNodes/Simple
+ *
+ * The contents of this file are subject to the terms of the
+ * Apache License Version 2 (the "APL"). You may not use this
+ * file except in compliance with the License. A copy of the
+ * APL may be obtained from:
+ * http://www.apache.org/licenses/LICENSE-2.0
+ */
+package com.seaofnodes.simple.lexer.ecstasy;
 
 import java.text.MessageFormat;
 
 import java.util.Arrays;
 
-import com.seaofnodes.simple.lexer.ecstasy.Source;
-
 import static com.seaofnodes.util.Handy.quotedString;
 
 
diff --git a/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Lexer.java b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Lexer.java
index 90571ffd..86a7b77f 100644
--- a/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Lexer.java
+++ b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Lexer.java
@@ -1,4 +1,4 @@
-/**
+/*
  * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
  *
  * Contributor(s):
@@ -28,10 +28,8 @@ import java.util.NoSuchElementException;
 
 import java.util.function.Consumer;
 
-import com.seaofnodes.simple.common.ErrorListener;
 import com.seaofnodes.simple.lexer.ecstasy.Token.Id;
 import com.seaofnodes.util.PackedInteger;
-import com.seaofnodes.simple.common.Severity;
 
 import static com.seaofnodes.util.Handy.*;
 
@@ -1076,6 +1074,17 @@ public class Lexer
                                 {
                                 switch (name)
                                     {
+                                    case "int":
+                                        idNum = Id.TYPE_INT;
+                                        break;
+                                    case "float":
+                                        idNum = Id.TYPE_FLOAT;
+                                        break;
+                                    case "char":
+                                        idNum = Id.TYPE_CHAR;
+                                        break;
+
+                                    // Following are Ecstasy ids
                                     case "Bit":
                                         idNum = Id.LIT_BIT;
                                         break;
diff --git a/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Severity.java b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Severity.java
new file mode 100644
index 00000000..9b01a7e4
--- /dev/null
+++ b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Severity.java
@@ -0,0 +1,36 @@
+/*
+ * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Contributor(s):
+ *
+ * The Initial Developer of the Original Software is
+ * The Ecstasy Project (https://github.com/xtclang/).
+ *
+ * This file is part of the Sea Of Nodes Simple Programming language
+ * implementation. See https://github.com/SeaOfNodes/Simple
+ *
+ * The contents of this file are subject to the terms of the
+ * Apache License Version 2 (the "APL"). You may not use this
+ * file except in compliance with the License. A copy of the
+ * APL may be obtained from:
+ * http://www.apache.org/licenses/LICENSE-2.0
+ */
+package com.seaofnodes.simple.lexer.ecstasy;
+
+
+/**
+ * Severity levels.
+ */
+public enum Severity
+    {
+    NONE, INFO, WARNING, ERROR, FATAL;
+
+    public String desc()
+        {
+        String sName = name();
+        StringBuilder sb = new StringBuilder(sName.length());
+        sb.append(sName.charAt(0));
+        sb.append(sName.substring(1).toLowerCase());
+        return sb.toString();
+        }
+    }
diff --git a/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Source.java b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Source.java
index 6800138a..c0da5d5f 100644
--- a/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Source.java
+++ b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Source.java
@@ -1,4 +1,4 @@
-/**
+/*
  * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
  *
  * Contributor(s):
diff --git a/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Token.java b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Token.java
index 271d8fbc..18cb5759 100644
--- a/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Token.java
+++ b/common/src/main/java/com/seaofnodes/simple/lexer/ecstasy/Token.java
@@ -1,4 +1,4 @@
-/**
+/*
  * DO NOT REMOVE COPYRIGHT NOTICES OR THIS HEADER.
  *
  * Contributor(s):
@@ -19,9 +19,6 @@
 package com.seaofnodes.simple.lexer.ecstasy;
 
 
-import com.seaofnodes.simple.common.ErrorListener;
-import com.seaofnodes.simple.common.Severity;
-
 import java.util.HashMap;
 import java.util.Map;
 
@@ -432,6 +429,9 @@ public class Token
             case LIT_FLOAT128:
             case LIT_FLOATN:
             case LIT_BFLOAT16:
+            case TYPE_INT:
+            case TYPE_FLOAT:
+            case TYPE_CHAR:
                 sb.append(m_id.TEXT)
                   .append(':')
                   .append(m_oValue);
@@ -637,6 +637,13 @@ public class Token
         IDENTIFIER   (null             ),
         EOL_COMMENT  (null             ),
         ENC_COMMENT  (null             ),
+
+        // Simple language type keywords
+        TYPE_INT     ("int"            , false, true),
+        TYPE_FLOAT   ("float"          , false, true),
+        TYPE_CHAR    ("char"           , false, true),
+        // End Simple language type keywords
+
         LIT_BIT      (null             ),
         LIT_NIBBLE   (null             ),
         LIT_CHAR     (null             ),
diff --git a/common/src/main/java/com/seaofnodes/util/Handy.java b/common/src/main/java/com/seaofnodes/util/Handy.java
index f3496f8c..62e34ab9 100644
--- a/common/src/main/java/com/seaofnodes/util/Handy.java
+++ b/common/src/main/java/com/seaofnodes/util/Handy.java
@@ -518,7 +518,7 @@ public class Handy
      */
     public static boolean isDigit(char ch)
         {
-        return ch >= '0' & ch <= '9';
+        return ch >= '0' && ch <= '9';
         }
 
     /**
@@ -547,7 +547,7 @@ public class Handy
         //   {..., 0, ..., 9, ..., A, ..., F, ..., a, ..., f, ...}
         // so a hexit has to be in the range 0..f, and the entire character
         // range from 0..f is only 0x36 (so it fits inside a long mask)
-        return ch >= '0' & ch <= 'f' & ((1L << ('f' - ch)) &
+        return ch >= '0' && ch <= 'f' && ((1L << ('f' - ch)) &
                 // 3               4               5               6
                 // 0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456
                 // 0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[/]^_`abcdef
@@ -579,7 +579,7 @@ public class Handy
         {
         // ASCII letters in the unicode range appear in this order:
         //   {..., A, ..., Z, ..., a, ..., z, ...}
-        return ch >= 'A' & ch <= 'z' & ((1L << ('z' - ch)) &
+        return ch >= 'A' && ch <= 'z' && ((1L << ('z' - ch)) &
                 // 4              5               6               7
                 // 123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789A
                 // ABCDEFGHIJKLMNOPQRSTUVWXYZ[/]^_`abcdefghijklmnopqrstuvwxyz
diff --git a/common/src/test/java/com/seaofnodes/simple/lexer/TestLexer.java b/common/src/test/java/com/seaofnodes/simple/lexer/TestLexer.java
index ef29d963..aec5d171 100644
--- a/common/src/test/java/com/seaofnodes/simple/lexer/TestLexer.java
+++ b/common/src/test/java/com/seaofnodes/simple/lexer/TestLexer.java
@@ -15,7 +15,7 @@
 
 package com.seaofnodes.simple.lexer;
 
-import com.seaofnodes.simple.common.ErrorListener;
+import com.seaofnodes.simple.lexer.ecstasy.ErrorListener;
 import com.seaofnodes.simple.lexer.ecstasy.Lexer;
 import com.seaofnodes.simple.lexer.ecstasy.Source;
 import com.seaofnodes.simple.lexer.ecstasy.Token;