1 files changed, 45 insertions, 0 deletions
diff --git a/st/TokenKey.java b/st/TokenKey.java
new file mode 100644
index 0000000..2319917
--- /dev/null
+++ b/st/TokenKey.java
@@ -0,0 +1,45 @@
+package st;
+
+/**
+ * This class is a data structure used to distinguish tokens in
+ * a given program. Tokens are considered unique if their "beginLine"
+ * and name are different.
+ */
+public class TokenKey {
+
+    private String name;
+    private int beginLine;
+
+    public TokenKey(String name, int beginLine) {
+        // classes CANNOT collide, so CALLEES ARE EXPECTED TO USE ZERO!
+        this.name = name;
+        this.beginLine = beginLine;
+    }
+
+    @Override public String toString() {
+        return String.format("%s (%d)",
+                             this.name,
+                             this.beginLine);
+    }
+
+
+    @Override public boolean equals(Object other) {
+        boolean ret = false;
+        TokenKey o;
+        if (other instanceof TokenKey &&
+            (o = (TokenKey) other).name == this.name &&
+            o.beginLine == this.beginLine) {
+            ret = true;
+        }
+        return ret;
+    }
+
+    @Override public int hashCode() {
+        return this.name.hashCode();
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+}