From ebbcb8774587347069b9aecaa517352ffbe7e30b Mon Sep 17 00:00:00 2001
From: Jonathan Bernard <jdbernard@gmail.com>
Date: Thu, 19 Nov 2009 09:57:41 -0600
Subject: [PATCH] Initial thoughts and groundwork for scoping, activation
 records, and functions.

---
 .../utexas/cs345/jdblisp/SpecialForms.java    | 14 +++++
 src/edu/utexas/cs345/jdblisp/SymbolTable.java | 52 +++++++++++++++++++
 src/edu/utexas/cs345/jdblisp/TableEntry.java  | 18 +++++++
 3 files changed, 84 insertions(+)
 create mode 100644 src/edu/utexas/cs345/jdblisp/SpecialForms.java
 create mode 100644 src/edu/utexas/cs345/jdblisp/SymbolTable.java
 create mode 100644 src/edu/utexas/cs345/jdblisp/TableEntry.java

diff --git a/src/edu/utexas/cs345/jdblisp/SpecialForms.java b/src/edu/utexas/cs345/jdblisp/SpecialForms.java
new file mode 100644
index 0000000..92dbf62
--- /dev/null
+++ b/src/edu/utexas/cs345/jdblisp/SpecialForms.java
@@ -0,0 +1,14 @@
+package edu.utexas.cs345.jdblisp;
+
+/**
+ * SpecialForms
+ * @author Jonathan Bernard (jdbernard@gmail.com)
+ */
+public class SpecialForms {
+
+    public static SymbolTable createTable() {
+
+    }
+
+    public static TableEntry 
+}
diff --git a/src/edu/utexas/cs345/jdblisp/SymbolTable.java b/src/edu/utexas/cs345/jdblisp/SymbolTable.java
new file mode 100644
index 0000000..f6ba111
--- /dev/null
+++ b/src/edu/utexas/cs345/jdblisp/SymbolTable.java
@@ -0,0 +1,52 @@
+package edu.utexas.cs345.jdblisp;
+
+/**
+ * SymbolTable
+ * @author Jonathan Bernard (jdbernard@gmail.com)
+ */
+public class SymbolTable {
+    public final TableEntry top;
+    public final SymbolTable rest;
+
+    public SymbolTable(TableEntry te, SymbolTable st) {
+        this.top = te;
+        this.rest = st;
+    }
+
+    public SymbolTable(TableEntry... te) {
+        int idx = te.length;
+        SymbolTable last = null;
+        while (idx > 1) last = new SymbolTable(te[--idx], last);
+
+        assert (--idx == 0) : "Error in SymbolTable construction. "
+            + "Invalid ending index";
+
+        this.top = te[0];
+        this.rest = last;
+    }
+
+    public TableEntry findFunction(Symbol symbol) throws LispException {
+        if (top.name.equals(symbol) && top.parameters != null)
+            return top;
+
+        if (rest == null)
+            throw new LispException("Undefined function: "
+                + symbol.name);
+
+        return rest.findFunction(symbol);
+    }
+
+    public TableEntry findVariable(Symbol symbol) throws LispException {
+        // if this entry is the one we're looking for, return it
+        if (top.name.equals(symbol) && top.parameters == null)
+            return top;
+
+        // if not, and there are no more entries
+        if (rest == null)
+            throw new LispException("Undefined variable: "
+                + symbol.name);
+
+        // otherwise, search the remainder of the table
+        return rest.findVariable(symbol);
+    }
+}
diff --git a/src/edu/utexas/cs345/jdblisp/TableEntry.java b/src/edu/utexas/cs345/jdblisp/TableEntry.java
new file mode 100644
index 0000000..348a792
--- /dev/null
+++ b/src/edu/utexas/cs345/jdblisp/TableEntry.java
@@ -0,0 +1,18 @@
+package edu.utexas.cs345.jdblisp;
+
+/**
+ * @author Jonathan Bernard (jdbernard@gmail.com)
+ */
+public class TableEntry {
+
+    public final Symbol name;
+    public final Symbol[] parameters;
+    public final SExp body;
+
+    public TableEntry(Symbol name, Symbol[] parameters, SExp body) {
+        this.name = name;
+        this.parameters = parameters;
+        this.body = body;
+    }
+
+}