From 53e2416426846fa1e57007a0029da90186411294 Mon Sep 17 00:00:00 2001
From: Riccardo Azzolini <riccardo4096@gmail.com>
Date: Tue, 16 Oct 2018 18:46:49 +0200
Subject: [PATCH] Implement EquationPattern

---
 .../rules/dsl/patterns/EquationPattern.java   | 39 +++++++++++++++++++
 .../warppi/math/rules/dsl/PatternTest.java    |  5 +++
 2 files changed, 44 insertions(+)
 create mode 100644 core/src/main/java/it/cavallium/warppi/math/rules/dsl/patterns/EquationPattern.java

diff --git a/core/src/main/java/it/cavallium/warppi/math/rules/dsl/patterns/EquationPattern.java b/core/src/main/java/it/cavallium/warppi/math/rules/dsl/patterns/EquationPattern.java
new file mode 100644
index 00000000..21350831
--- /dev/null
+++ b/core/src/main/java/it/cavallium/warppi/math/rules/dsl/patterns/EquationPattern.java
@@ -0,0 +1,39 @@
+package it.cavallium.warppi.math.rules.dsl.patterns;
+
+import it.cavallium.warppi.math.Function;
+import it.cavallium.warppi.math.MathContext;
+import it.cavallium.warppi.math.functions.Sum;
+import it.cavallium.warppi.math.functions.equations.Equation;
+import it.cavallium.warppi.math.rules.dsl.Pattern;
+import it.cavallium.warppi.math.rules.dsl.PatternUtils;
+import it.cavallium.warppi.math.rules.dsl.VisitorPattern;
+
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * Matches and generates an equation of two other patterns.
+ */
+public class EquationPattern extends VisitorPattern {
+    private final Pattern left;
+    private final Pattern right;
+
+    public EquationPattern(final Pattern left, final Pattern right) {
+        this.left = left;
+        this.right = right;
+    }
+
+    @Override
+    public Optional<Map<String, Function>> visit(final Equation equation) {
+        return PatternUtils.matchFunctionOperatorParameters(equation, left, right);
+    }
+
+    @Override
+    public Function replace(final MathContext mathContext, final Map<String, Function> subFunctions) {
+        return new Equation(
+                mathContext,
+                left.replace(mathContext, subFunctions),
+                right.replace(mathContext, subFunctions)
+        );
+    }
+}
diff --git a/core/src/test/java/it/cavallium/warppi/math/rules/dsl/PatternTest.java b/core/src/test/java/it/cavallium/warppi/math/rules/dsl/PatternTest.java
index a8f76b19..c2d81c5f 100644
--- a/core/src/test/java/it/cavallium/warppi/math/rules/dsl/PatternTest.java
+++ b/core/src/test/java/it/cavallium/warppi/math/rules/dsl/PatternTest.java
@@ -4,6 +4,7 @@ import it.cavallium.warppi.math.Function;
 import it.cavallium.warppi.math.MathContext;
 import it.cavallium.warppi.math.functions.*;
 import it.cavallium.warppi.math.functions.Number;
+import it.cavallium.warppi.math.functions.equations.Equation;
 import it.cavallium.warppi.math.functions.trigonometry.*;
 import it.cavallium.warppi.math.rules.dsl.patterns.*;
 import org.apache.commons.lang3.tuple.ImmutablePair;
@@ -142,6 +143,10 @@ public class PatternTest {
                         new DivisionPattern(x, y),
                         new Division(mathContext, one, two)
                 ),
+                new ImmutablePair<>(
+                        new EquationPattern(x, y),
+                        new Equation(mathContext, one, two)
+                ),
                 new ImmutablePair<>(
                         new LogarithmPattern(x, y),
                         new Logarithm(mathContext, one, two)