Update README

Add true/false

3 files changed, 63 insertions, 30 deletions

diff --git a/chapter05/README.md b/chapter05/README.md
index bea9545b..8929dfad 100644
--- a/chapter05/README.md
+++ b/chapter05/README.md
@@ -31,47 +31,65 @@ Here is a recap of the nodes introduced in previous chapters:
 
 Following new nodes are introduced in this chapter:
 
-| Node Name | Type    | Chapter | Description                                                          | Inputs                                                                                         | Value                                                         |
-|-----------|---------|---------|----------------------------------------------------------------------|------------------------------------------------------------------------------------------------|---------------------------------------------------------------|
-| If        | Control | 5       | Represents an `if` condition, sub type of `MultiNode`                | A control node and a data predicate node                                                       | A tuple of two values, one for true branch, another for false |
-| Region    | Control | 5       | Represents a merge point from multiple control flow                  | An input for each control flow that is merging                                                 | Merged control                                                |
-| Phi       | Data    | 5       | Represents the phi function that picks a value based on control flow | A region control node, and multiple data nodes that provide values from multiple control flows | Result is the extracted value depending on control flow taken | 
-| Stop      | Control | 5       | Represents termination of the program                                | One or more Return nodes                                                                       | None                                                          |
+| Node Name | Type    | Chapter | Description                                        | Inputs                                         | Value                                              |
+|-----------|---------|---------|----------------------------------------------------|------------------------------------------------|----------------------------------------------------|
+| If        | Control | 5       | A branching test, sub type of `MultiNode`          | A control node and a data predicate node       | A tuple of two values: one for true, one for false |
+| Region    | Control | 5       | A merge point for multiple control flow            | An input for each control flow that is merging | Merged control                                     |
+| Phi       | Data    | 5       | A phi function picks a value based on control flow | A Region, and data nodes for each control path | Depends on control flow path taken                 | 
+| Stop      | Control | 5       | Termination of the program                         | One or more Return nodes                       | None                                               |
 
 ## `If` Nodes
 
-`If` node takes in both control and data (predicate expression) and routes the control token to one of the two control flows, represented by the `Proj` nodes.
+`If` node takes in both control and data (predicate expression) and routes the
+control token to one of the two control flows, represented by true and false
+`Proj` nodes.
 
 ## `Phi` Nodes
 
-The `Phi` reads in both data and control, and outputs a data value. The control input to the `Phi` points to a `Region` node. The data inputs to the `Phi` are one each for the control inputs to that `Region`.
-The result computed by a `Phi` depends both on the data and the matching control input. At most one control input to the `Region` can be active at a time. The `Phi` passes through the data value from the matching input [[1]](#1).
+A `Phi` reads in both data and control, and outputs a data value.  The control
+input to the `Phi` points to a `Region` node.  The data inputs to the `Phi` are
+one each for the control inputs to that `Region`.  The result computed by a
+`Phi` depends both on the data and the matching control input.  At most one
+control input to the `Region` can be active at a time, and the `Phi` passes
+through the data value from the matching input [[1]](#1).
 
 ## `Region` Nodes
 
-`Region` nodes were originally introduced to replace Basic Blocks in the IR [[3]](#3). However, we do not assign a `Region` to every node in the graph; we insert a `Region` node at a merge point where it takes control from each predecessor control edge, and produces 
-a merged control as output. Data flows via `Phi` nodes at these merge points.
+`Region` nodes were originally introduced to replace Basic Blocks in the IR
+[[3]](#3).  However, we do not assign a `Region` to every node in the graph; we
+insert a `Region` node at a merge point where it takes control from each
+predecessor control edge, and produces a merged control as output.  Data flows
+via `Phi` nodes at these merge points.
 
 ## Parsing of `If` statement
 
-When we parse an `if` statement, the control flow splits at that point. We must track the names being updated in each part of the `if` statement, and then merge them at the end.
-The implementation follows the description in [[2]](#2).
+When we parse an `if` statement, the control flow splits at that point.  We
+must track the names being updated in each part of the `if` statement, and then
+merge them at the end.  The implementation follows the description in
+[[2]](#2).
 
 This involves following:
 
-* We create an `IfNode` with the current control token, i.e. the node mapped to `$ctrl`, and the `if` predicate expression as inputs.
-* We add two `ProjNodes` - one for the `True` branch (call if `ifT`), and the other for the `False` branch (call it `ifF`) - these extract values from the tuple result of the `IfNode`.
-* We duplicate the current `ScopeNode`. The duplicated `ScopeNode` contains all the stack levels as the original, and moreover the new node is added as a user of all the names that are currently bound.
-* The original `ScopeNode` is saved.
-* We set the duplicate `ScopeNode` as current.
-* We set control token to the `True` projection node `ifT`.
-* We parse the true branch of the `if` statement.
-* We reset the original `ScopeNode` as current.
-* We set control token to the `False` projection node `ifF`.
-* If there is an `else` statement we parse it.
-* At this point we have two `ScopeNode`s; the original one, potentially updated by the `False` branch, and the duplicate one, potentially updated by the `True` branch.
+* We create an `IfNode` with the current control token, i.e. the node mapped to
+  `$ctrl`, and the `if` predicate expression as inputs.
+* We add two `ProjNodes` - one for the `True` branch (call if `ifT`), and the
+  other for the `False` branch (call it `ifF`) - these extract values from the
+  tuple result of the `IfNode`.
+* We duplicate the current `ScopeNode`.  The duplicated `ScopeNode` contains
+  all the same symbol tables as the original, and has the same edges.
+* We set control token to the `True` projection node `ifT`, and parse the true
+  branch of the `if` statement.
+* We reset the dupped `ScopeNode` as current.
+* We set control token to the `False` projection node `ifF`, and if there is an
+  `else` statement we parse it.
+* At this point we have two `ScopeNode`s; the original one, potentially updated
+  by the `True` branch, and the duplicate one, potentially updated by the
+  `False` branch.  
 * We create a `Region` node to represent a merge point.
-* We compare the two `ScopeNode`s. We create `Phi` nodes for any names whose bindings differ. The `Phi` nodes take the `Region` node as the control input and the two data nodes from each of the `ScopeNode`s. The name binding is updated to point to the `Phi` node.
+* We *merge* the two `ScopeNode`s. We create `Phi` nodes for any names whose
+  bindings differ.  The `Phi` nodes take the `Region` node as the control input
+  and the two data nodes from each of the `ScopeNode`s.  The name binding is
+  updated to point to the `Phi` node.
 * Finally, we set the `Region` node as the control token, and discard the duplicated `ScopeNode`.
 
 ## Example
diff --git a/chapter05/src/main/java/com/seaofnodes/simple/Parser.java b/chapter05/src/main/java/com/seaofnodes/simple/Parser.java
index 3e832610..a23f8d70 100644
--- a/chapter05/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter05/src/main/java/com/seaofnodes/simple/Parser.java
@@ -280,17 +280,19 @@ public class Parser {
      * Parse a primary expression:
      *
      * <pre>
-     *     primaryExpr : integerLiteral | Identifier | '(' expression ')'
+     *     primaryExpr : integerLiteral | Identifier | true | false | '(' expression ')'
      * </pre>
      */
     private Node parsePrimary() {
-        if (_lexer.isNumber()) return parseIntegerLiteral();
-        if (match("(")) return require(parseExpression(), ")");
+        if( _lexer.isNumber() ) return parseIntegerLiteral();
+        if( match("(") ) return require(parseExpression(), ")");
+        if( match("true" ) ) return new ConstantNode(TypeInteger.constant(1)).peephole();
+        if( match("false") ) return new ConstantNode(TypeInteger.constant(0)).peephole();
         String name = requireId();
         Node id = _scope.lookup(name);
         if( id==null )
             throw error("Undefined name '" + name + "'");
-        return id.peephole();
+        return id;
     }
 
     /**
diff --git a/chapter05/src/test/java/com/seaofnodes/simple/Chapter05Test.java b/chapter05/src/test/java/com/seaofnodes/simple/Chapter05Test.java
index e59d1dbd..8f09620e 100644
--- a/chapter05/src/test/java/com/seaofnodes/simple/Chapter05Test.java
+++ b/chapter05/src/test/java/com/seaofnodes/simple/Chapter05Test.java
@@ -62,7 +62,14 @@ return c;
         StopNode ret = parser.parse();
         assertEquals("return (Phi(Region31,(arg+1),(arg+3))+Phi(Region31,((arg*2)+3),(arg+2)));", ret.toString());
     }
-      
+
+    @Test
+    public void testChapter5Merge3() {
+        Parser parser = new Parser("int a=1; if( arg==1 ) if( arg==2 ) a=2; else a=3; else if( arg==3 ) a=4; else a=5; return a; #showGraph;", TypeInteger.BOT);
+        StopNode stop = parser.parse();
+        assertEquals("return Phi(Region33,Phi(Region21,2,3),Phi(Region31,4,5));", stop.toString());
+    }
+
     @Test
     public void testChapter5HalfDef() {
         try { 
@@ -82,6 +89,12 @@ return c;
             assertEquals("Undefined name 'b'",e.getMessage());
         }
     }
+    
+    @Test
+    public void testChapter5True() {
+      StopNode stop = new Parser("return true;").parse();
+      assertEquals("return 1;",stop.toString());
+    }
       
     @Test
     public void testChapter4Peephole() {