From 187c926017542244450f52642af98c52e889b2e9 Mon Sep 17 00:00:00 2001
From: Rob Greene <robgreene@gmail.com>
Date: Sun, 10 Jun 2018 10:38:08 -0500
Subject: [PATCH] Utility to generate all Applesoft variable names.

---
 .../api/utils/VariableNameGenerator.java      | 28 +++++++++++++
 .../api/utils/VariableNameGeneratorTest.java  | 41 +++++++++++++++++++
 2 files changed, 69 insertions(+)
 create mode 100644 api/src/main/java/io/github/applecommander/bastokenizer/api/utils/VariableNameGenerator.java
 create mode 100644 api/src/test/java/io/github/applecommander/bastokenizer/api/utils/VariableNameGeneratorTest.java

diff --git a/api/src/main/java/io/github/applecommander/bastokenizer/api/utils/VariableNameGenerator.java b/api/src/main/java/io/github/applecommander/bastokenizer/api/utils/VariableNameGenerator.java
new file mode 100644
index 0000000..056c023
--- /dev/null
+++ b/api/src/main/java/io/github/applecommander/bastokenizer/api/utils/VariableNameGenerator.java
@@ -0,0 +1,28 @@
+package io.github.applecommander.bastokenizer.api.utils;
+
+import java.util.Optional;
+import java.util.function.Supplier;
+
+/** Generate all Applesoft BASIC FP variable names. */
+public class VariableNameGenerator implements Supplier<Optional<String>> {
+	public static final String CHAR1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+	public static final String CHAR2 = " " + CHAR1 + "0123456789";
+	public static final int LENGTH = CHAR1.length() * CHAR2.length();
+
+	private int n = 0;
+	
+	@Override
+	public Optional<String> get() {
+		try {
+			if (n >= 0 && n < LENGTH) {
+				return Optional.of(String.format("%s%s", 
+										CHAR1.charAt(n % CHAR1.length()), 
+										CHAR2.charAt(n / CHAR1.length())
+									).trim());
+			}
+			return Optional.empty();
+		} finally {
+			n += 1;
+		}
+	}
+}
diff --git a/api/src/test/java/io/github/applecommander/bastokenizer/api/utils/VariableNameGeneratorTest.java b/api/src/test/java/io/github/applecommander/bastokenizer/api/utils/VariableNameGeneratorTest.java
new file mode 100644
index 0000000..cd9269b
--- /dev/null
+++ b/api/src/test/java/io/github/applecommander/bastokenizer/api/utils/VariableNameGeneratorTest.java
@@ -0,0 +1,41 @@
+package io.github.applecommander.bastokenizer.api.utils;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Test;
+
+public class VariableNameGeneratorTest {
+	@Test
+	public void testNameSequence() {
+		Map<Integer,String> expecteds = new HashMap<>();
+		expecteds.put(0, "A");
+		expecteds.put(25, "Z");
+		expecteds.put(26, "AA");
+		expecteds.put(51, "ZA");
+		expecteds.put(52, "AB");
+		expecteds.put(77, "ZB");
+		// very last name in sequence
+		expecteds.put(VariableNameGenerator.LENGTH-1, "Z9");
+		
+		int lastCheck = expecteds.keySet().stream().max(Integer::compare).get();
+		
+		VariableNameGenerator gen = new VariableNameGenerator();
+		for (int i = 0; i <= lastCheck; i++) {
+			String varName = gen.get().orElseThrow(() -> new RuntimeException("Ran out of variable names too early!"));
+			if (expecteds.containsKey(i)) {
+				assertEquals(expecteds.get(i), varName);
+			}
+		}
+	}
+	
+	@Test
+	public void testSequenceLength() {
+		VariableNameGenerator gen = new VariableNameGenerator();
+		int count = 0;
+		while (gen.get().isPresent()) count++;
+		assertEquals(VariableNameGenerator.LENGTH, count);
+	}
+}