1 files changed, 72 insertions, 0 deletions
diff --git a/Homework/cs5300/homework-two/Infix.java b/Homework/cs5300/homework-two/Infix.java
new file mode 100644
index 0000000..33c8dcf
--- /dev/null
+++ b/Homework/cs5300/homework-two/Infix.java
@@ -0,0 +1,72 @@
+import java.util.ArrayList;
+import java.io.IOException;
+
+public class Infix {
+    private ArrayList<Character> chars;
+    private int index;
+    
+    public static void main(String[] args) {
+        String str = "+++12-835";
+        if (args.length > 0) {
+            str = args[0];
+        }
+        try {
+            Infix parser = new Infix(str);
+        } catch (Exception e) {
+            System.out.println("error");
+        }
+    }
+    
+    public Infix(String terminals) throws IOException {
+        this.index = 0;
+        this.chars = new ArrayList<Character>();
+        for (char c: terminals.toCharArray()) 
+            this.chars.add(c);
+        
+        this.list();
+
+        if (this.index < this.chars.size())
+            throw new IOException("Could not parse entire string");
+        
+        System.out.println();
+    }
+
+    private void list() throws IOException {
+        char lookahead = this.lookahead();
+        if (lookahead == '+' || lookahead == '-') {
+            match(lookahead);
+            System.out.write('(');
+            list();
+            System.out.write(lookahead);
+            list();
+            System.out.write(')');
+        }
+        else if (lookahead >= '0' && lookahead <= '9') 
+            digit();
+        else 
+            throw new IOException("Expected lookahead to be a digit or plus/minus");
+    }
+
+    private void digit() throws IOException {
+        char lookahead = this.lookahead();
+        if (lookahead >= '0' && lookahead <= '9') {
+            match(lookahead);
+            System.out.write(lookahead);
+            return;
+        }
+        throw new IOException("Expected lookahead to be a digit");
+    }
+
+    private void match(char t) throws IOException {
+        boolean matches = this.lookahead() == t;
+
+        if (matches) 
+            this.index += 1;
+        else if (!matches) 
+            throw new IOException("Expected " + (char)this.lookahead() + " to match " + (char)t);
+    }
+
+    private char lookahead() {
+        return this.chars.get(this.index);
+    }
+}