From 4c0f972c4616eb549a098c3ef40d527eb542d7a6 Mon Sep 17 00:00:00 2001
From: Ben Culkin <scorpress@gmail.com>
Date: Sat, 21 Nov 2020 16:51:04 -0500
Subject: Add basic pattern matching

Adds a basic pattern matching implementation. Not perfect, but pretty
good, considering what we have to work with
---
 .../java/bjc/utils/patterns/FunctionalPattern.java | 47 ++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 base/src/main/java/bjc/utils/patterns/FunctionalPattern.java

(limited to 'base/src/main/java/bjc/utils/patterns/FunctionalPattern.java')

diff --git a/base/src/main/java/bjc/utils/patterns/FunctionalPattern.java b/base/src/main/java/bjc/utils/patterns/FunctionalPattern.java
new file mode 100644
index 0000000..e4b4a3d
--- /dev/null
+++ b/base/src/main/java/bjc/utils/patterns/FunctionalPattern.java
@@ -0,0 +1,47 @@
+package bjc.utils.patterns;
+
+import java.util.*;
+import java.util.function.*;
+
+import bjc.data.*;
+
+class FunctionalPattern<ReturnType, PredType, InputType>
+	implements ComplexPattern<ReturnType, PredType, InputType> {
+	private final Function<InputType, IPair<Boolean, PredType>> matcher;
+	private final BiFunction<InputType, PredType, ReturnType> accepter;
+
+	FunctionalPattern(
+			Function<InputType, IPair<Boolean, PredType>> matcher,
+			BiFunction<InputType, PredType, ReturnType> accepter) {
+		super();
+		this.matcher = matcher;
+		this.accepter = accepter;
+	}
+
+	@Override
+	public IPair<Boolean, PredType> matches(InputType input) {
+		return matcher.apply(input);
+	}
+	
+	@Override
+	public ReturnType apply(InputType input, PredType state) {
+		return accepter.apply(input, state);
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(accepter, matcher);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)                  return true;
+		if (obj == null)                  return false;
+		if (getClass() != obj.getClass()) return false;
+		
+		FunctionalPattern<?, ?, ?> other = (FunctionalPattern<?, ?, ?>) obj;
+		
+		return Objects.equals(accepter, other.accepter)
+				&& Objects.equals(matcher, other.matcher);
+	}
+}
\ No newline at end of file
-- 
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