Chapter 2 (#4)

* Start on Chapter 2.

* Start on Chapter 2.

* Refactor

* Refactor

* Initial attempt at peephole opt for add operation

* cleanup unused import

* Start on graph visualizer

* Start on graph visualizer

* Rework chapter 2

Add a short discourse on the Types, and provide a Bottom type.

Make a final toString; require each Node to specify its special printing via label().

Add a recursing printer called print(); toString is used by default in the debugger and so cannot be recursive.

Make the peephole rules based on a proper Type and idealize calls.
Big comments about the Type computations.

Every node picks up a _print, compute and idealize() call.

Rename long arith ops Divide, UnaryMinus, Multiply, Subtract into shorter uniform-length names.  Cleans up the parser where he does the precedence op parsing.

Rework Parser:
- Drop Token class, its all Strings except in the one place we know a number is coming
- Embed the Lexer as a field in the Parser, instead of trying to pass it around everywhere in the Parser
- StartNode becomes a read-only global, so we don't have to pass it around everywhere in the Parser AND optimizer.
- Lexer matches on strings and returns strings.  Match and consume *at the moment* instead of carrying around a current token/string and forcing the next-token after consuming the current one.
- All parse subexpressions shrink by 1/2 after these changes.

* Initial writeup of Chapter 2

* Initial writeup of Chapter 2

* Initial writeup of Chapter 2

* Initial writeup of Chapter 2

* Remove range

* progress Chapter 2

Drop integer ranges.
Broader lattice pic.
Lots of prose changes in the readme.
Fixed title in gviz dot generation.
Fixed bug with peephole making redundant constants.

* Implement compute for all the arithmetic node types
Add a flag to switch off peephole so we can see the full graph
Add post peephole graph to writeup

* Implement compute for all the arithmetic node types
Add a flag to switch off peephole so we can see the full graph
Add post peephole graph to writeup

* Fix bad path to the svg

* Update pre-peephole diagram

* Add dead code elimination

...and a set_def to proper update graph edges.

* Update README.md

* Cleanup the GraphVisualizer a bit.
Update the graphs.
Update the chapter list as chapter 3 deleted, and chapter 4 is now chapter 3.

---------

Co-authored-by: Cliff Click <cliffc@acm.org>

6 files changed, 6 insertions, 5 deletions

diff --git a/chapter01/README.md b/chapter01/README.md
index f3231d8c..57caa801 100644
--- a/chapter01/README.md
+++ b/chapter01/README.md
@@ -113,7 +113,7 @@ Here is visualization of the program:
 return 1;
 ```
 
-![Sea of Nodes Visual](./docs/02-graph.svg)
+![Sea of Nodes Visual](./docs/01-graph.svg)
 
 * Control nodes appear as square boxes
 * Control edges are in bold red
diff --git a/chapter01/docs/01-grammar.md b/chapter01/docs/01-grammar.md
index cf947dfc..5d9f3cf7 100644
--- a/chapter01/docs/01-grammar.md
+++ b/chapter01/docs/01-grammar.md
@@ -21,5 +21,6 @@ primaryExpression
 
 INTEGER_LITERAL
     : [1-9][0-9]*
+    | [0]
     ;    
 ```
\ No newline at end of file
diff --git a/chapter01/docs/02-graph.gv b/chapter01/docs/01-graph.gv
index 40181544..40181544 100644
--- a/chapter01/docs/02-graph.gv
+++ b/chapter01/docs/01-graph.gv
diff --git a/chapter01/docs/02-graph.svg b/chapter01/docs/01-graph.svg
index fbf92d7d..fbf92d7d 100644
--- a/chapter01/docs/02-graph.svg
+++ b/chapter01/docs/01-graph.svg
diff --git a/chapter01/src/main/java/com/seaofnodes/simple/Parser.java b/chapter01/src/main/java/com/seaofnodes/simple/Parser.java
index 8fb1ebaf..cdfff842 100644
--- a/chapter01/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter01/src/main/java/com/seaofnodes/simple/Parser.java
@@ -80,7 +80,7 @@ public class Parser {
      * Parse integer literal
      *
      * <pre>
-     *     integerLiteral: [1-9][0-9]*
+     *     integerLiteral: [1-9][0-9]* | [0]
      * </pre>
      */
     private ConstantNode parseIntegerLiteral(Lexer lexer) {
@@ -245,7 +245,7 @@ public class Parser {
 
         private Token parsePuncuation() {
             int start = _position-1;
-            while( isPunctuation(nextChar()) );
+            if( isPunctuation(nextChar()) );
             return Token.newPunct(new String(_input,start,--_position-start));            
         }
             
diff --git a/chapter01/src/test/java/com/seaofnodes/simple/ParserTest.java b/chapter01/src/test/java/com/seaofnodes/simple/Chapter01Test.java
index 887f63b8..14c22437 100644
--- a/chapter01/src/test/java/com/seaofnodes/simple/ParserTest.java
+++ b/chapter01/src/test/java/com/seaofnodes/simple/Chapter01Test.java
@@ -4,7 +4,7 @@ import com.seaofnodes.simple.node.*;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
-public class ParserTest {
+public class Chapter01Test {
 
     @Test
     public void testSimpleProgram() {
@@ -54,7 +54,7 @@ public class ParserTest {
     @Test
     public void testBad3() {
         try { new Parser().parse("return --12;"); }
-        catch( RuntimeException e ) { assertEquals("syntax error, expected integer literal: --",e.getMessage()); }
+        catch( RuntimeException e ) { assertEquals("syntax error, expected integer literal: -",e.getMessage()); }
     }
 
     @Test