Backport empty statement fix

Split Ch13 tests from Chapter12Test.java
Handle forward refs never defined.

3 files changed, 171 insertions, 114 deletions

diff --git a/chapter13/src/main/java/com/seaofnodes/simple/Parser.java b/chapter13/src/main/java/com/seaofnodes/simple/Parser.java
index fee5215e..f04bf5c3 100644
--- a/chapter13/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter13/src/main/java/com/seaofnodes/simple/Parser.java
@@ -167,6 +167,7 @@ public class Parser {
         else if (matchx("continue")) return parseContinue();
         else if (matchx("struct")  ) return parseStruct();
         else if (matchx("#showGraph")) return require(showGraph(),";");
+        else if (matchx(";")       ) return null; // Empty statement
         // declarations of vars with struct type are handled in parseExpressionStatement due
         // to ambiguity
         else return parseExpressionStatement();
@@ -190,7 +191,7 @@ public class Parser {
      * Only allowed in top level scope.
      * Structs cannot be redefined.
      *
-     * @return The statement following the struct
+     * @return null
      */
     private Node parseStruct() {
         if (_xScopes.size() > 1) throw errorSyntax("struct declarations can only appear in top level scope");
@@ -209,7 +210,7 @@ public class Parser {
         TypeStruct ts = TypeStruct.make(typeName, fields);
         TYPES.put(typeName, ts);
         START.addMemProj(ts, _scope); // Insert memory edges
-        return parseStatement();
+        return null;
     }
 
     /**
@@ -579,7 +580,8 @@ public class Parser {
         if( matchx("new") ) {
             String structName = requireId();
             Type t = TYPES.get(structName);
-            if( t == null || !(t instanceof TypeStruct obj) ) throw errorSyntax("Unknown struct type '" + structName + "'");
+            if( !(t instanceof TypeStruct obj) || obj._fields==null )
+                throw error("Unknown struct type '" + structName + "'");
             return newStruct(obj);
         }
         String name = _lexer.matchId();
diff --git a/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index 8eceb0fa..f711607b 100644
--- a/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/chapter13/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -60,115 +60,4 @@ return x+1==x;
         assertEquals(0L, Evaluator.evaluate(stop, 1));
     }
 
-
-    @Test
-    public void testLinkedList0() {
-        Parser parser = new Parser(
-"""
-struct LLI { LLI? next; int i; }
-LLI? head = null;
-while( arg ) {
-    LLI x = new LLI;
-    x.next = head;
-    x.i = arg;
-    head = x;
-    arg = arg-1;
-}
-return head.next.i;
-""");
-        try { parser.parse(true).iterate(true); fail(); }
-        catch( Exception e ) { assertEquals("Might be null accessing 'i'",e.getMessage()); }
-    }
-
-    @Test
-    public void testLinkedList1() {
-        Parser parser = new Parser(
-"""
-struct LLI { LLI? next; int i; }
-LLI? head = null;
-while( arg ) {
-    LLI x = new LLI;
-    x.next = head;
-    x.i = arg;
-    head = x;
-    arg = arg-1;
-}
-if( !head ) return 0;
-LLI? next = head.next;
-if( next==null ) return 1;
-return next.i;
-""");
-        StopNode stop = parser.parse(false).iterate(false);
-        assertEquals("Stop[ return 0; return 1; return .i; ]", stop.toString());
-        assertEquals(2L, Evaluator.evaluate(stop,  3));
-    }
-
-    @Test
-    public void testCoRecur() {
-        Parser parser = new Parser(
-"""
-struct int0 { int i; flt0? f; }
-struct flt0 { flt f; int0? i; }
-int0 i0 = new int0;
-i0.i = 17;
-flt0 f0 = new flt0;
-f0.f = 3.14;
-i0.f = f0;
-f0.i = i0;
-return f0.i.f.i.i;
-""");
-        StopNode stop = parser.parse(false).iterate(false);
-        assertEquals("return 17;", stop.toString());
-    }
-
-    @Test
-    public void testNullRef0() {
-        Parser parser = new Parser(
-"""
-struct N { N next; int i; }
-N n = new N;
-return n.next;
-""");
-        StopNode stop = parser.parse(false).iterate(false);
-        assertEquals("return null;", stop.toString());
-    }
-
-    @Test
-    public void testNullRef1() {
-        Parser parser = new Parser(
-"""
-struct N { N next; int i; }
-N n = new N;
-n.next = new N;
-return n.next;
-""");
-        StopNode stop = parser.parse(false).iterate(false);
-        assertEquals("return new N;", stop.toString());
-    }
-
-    @Test
-    public void testNullRef2() {
-        Parser parser = new Parser(
-"""
-struct N { N next; int i; }
-N n = new N;
-n.next = null;
-return n.next;
-""");
-        try { parser.parse(true).iterate(true); fail(); }
-        catch( Exception e ) { assertEquals("Cannot store null into field *N next",e.getMessage()); }
-    }
-
-    @Test
-    public void testNullRef3() {
-        Parser parser = new Parser(
-"""
-struct N { N next; int i; }
-N n = new N;
-n.i = 3.14;
-return n.i;
-""");
-        try { parser.parse(true).iterate(true); fail(); }
-        catch( Exception e ) { assertEquals("Cannot store 3.14 into field IntBot i",e.getMessage()); }
-    }
 }
diff --git a/chapter13/src/test/java/com/seaofnodes/simple/Chapter13Test.java b/chapter13/src/test/java/com/seaofnodes/simple/Chapter13Test.java
new file mode 100644
index 00000000..f7d4d5a8
--- /dev/null
+++ b/chapter13/src/test/java/com/seaofnodes/simple/Chapter13Test.java
@@ -0,0 +1,166 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.evaluator.Evaluator;
+import com.seaofnodes.simple.node.StopNode;
+import org.junit.Ignore;
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+public class Chapter13Test {
+    @Test
+    public void testJig() {
+        Parser parser = new Parser(
+"""
+return 3.14;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return 3.14;", stop.toString());
+        assertEquals(3.14, Evaluator.evaluate(stop,  0));
+    }
+
+    @Test
+    public void testLinkedList0() {
+        Parser parser = new Parser(
+"""
+struct LLI { LLI? next; int i; }
+LLI? head = null;
+while( arg ) {
+    LLI x = new LLI;
+    x.next = head;
+    x.i = arg;
+    head = x;
+    arg = arg-1;
+}
+return head.next.i;
+""");
+        try { parser.parse(true).iterate(true); fail(); }
+        catch( Exception e ) { assertEquals("Might be null accessing 'i'",e.getMessage()); }
+    }
+
+    @Test
+    public void testLinkedList1() {
+        Parser parser = new Parser(
+"""
+struct LLI { LLI? next; int i; }
+LLI? head = null;
+while( arg ) {
+    LLI x = new LLI;
+    x.next = head;
+    x.i = arg;
+    head = x;
+    arg = arg-1;
+}
+if( !head ) return 0;
+LLI? next = head.next;
+if( next==null ) return 1;
+return next.i;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("Stop[ return 0; return 1; return .i; ]", stop.toString());
+        assertEquals(2L, Evaluator.evaluate(stop,  3));
+    }
+
+    @Test
+    public void testCoRecur() {
+        Parser parser = new Parser(
+"""
+struct int0 { int i; flt0? f; }
+struct flt0 { flt f; int0? i; }
+int0 i0 = new int0;
+i0.i = 17;
+flt0 f0 = new flt0;
+f0.f = 3.14;
+i0.f = f0;
+f0.i = i0;
+return f0.i.f.i.i;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return 17;", stop.toString());
+    }
+
+    @Test
+    public void testNullRef0() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+return n.next;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return null;", stop.toString());
+    }
+
+    @Test
+    public void testNullRef1() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+n.next = new N;
+return n.next;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return new N;", stop.toString());
+    }
+
+    @Test
+    public void testNullRef2() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+n.next = null;
+return n.next;
+""");
+        try { parser.parse(true).iterate(true); fail(); }
+        catch( Exception e ) { assertEquals("Cannot store null into field *N next",e.getMessage()); }
+    }
+
+    @Test
+    public void testNullRef3() {
+        Parser parser = new Parser(
+"""
+struct N { N next; int i; }
+N n = new N;
+n.i = 3.14;
+return n.i;
+""");
+        try { parser.parse(true).iterate(true); fail(); }
+        catch( Exception e ) { assertEquals("Cannot store 3.14 into field IntBot i",e.getMessage()); }
+    }
+
+    @Test
+    public void testEmpty() {
+        Parser parser = new Parser(
+"""
+struct S{};
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return 0;", stop.toString());
+        assertEquals(0L, Evaluator.evaluate(stop,  0));
+    }
+
+    @Test
+    public void testForwardRef0() {
+        Parser parser = new Parser(
+"""
+struct S1 { S2 s; }
+return new S2;
+""");
+        try { parser.parse(true).iterate(true); fail(); }
+        catch( Exception e ) { assertEquals("Unknown struct type 'S2'",e.getMessage()); }
+    }
+
+    @Test
+    public void testForwardRef1() {
+        Parser parser = new Parser(
+"""
+struct S1 { S2? s; }
+struct S2 { int x; }
+return new S1.s=new S2;
+""");
+        StopNode stop = parser.parse(false).iterate(false);
+        assertEquals("return new S1;", stop.toString());
+    }
+}