Merge pull request #52 from javecs/feature/function

ユーザー関数（Function）を実装しました。

Author: javecs

src/main/kotlin/xyz/javecs/tools/expr/Function.kt

@@ -0,0 +1,27 @@
+package xyz.javecs.tools.expr
+
+import kotlin.streams.toList
+
+private val sPattern = Regex("[a-zA-Z][a-zA-Z0-9]*\\s*\\(\\s*([a-zA-Z][a-zA-Z0-9]*\\s*(,\\s*[a-zA-Z][a-zA-Z0-9]*)*)?\\s*\\)")
+internal fun validate(signature: String): Pair<String, Array<String>> {
+    if (!sPattern.matches(signature.trim())) throw Exception()
+    val separated = signature.replace(" ", "").split("(", ",", ")").stream().filter { !it.isBlank() }.toList()
+    return Pair(separated[0], if (separated.size > 1) {
+        separated.subList(1, separated.size).toTypedArray()
+    } else {
+        emptyArray()
+    })
+}
+
+class Function(signature: String, val codes: Array<String>) {
+    private val calc = Calculator()
+    val name = validate(signature).first
+    val params = validate(signature).second
+    fun call(args: Array<Double>): Double {
+        if (params.size != args.size) return Double.NaN
+        calc.clear()
+        params.indices.forEach( { calc.eval("${params[it]} = ${args[it]}") })
+        codes.forEach( { calc.eval(it) })
+        return calc.value.toDouble()
+    }
+}

src/test/kotlin/xyz/javecs/tools/expr/test/kotlin/FunctionCallTest.kt

@@ -0,0 +1,43 @@
+package xyz.javecs.tools.expr.test.kotlin
+
+import kotlin.test.assertEquals
+import org.junit.Test
+import xyz.javecs.tools.expr.Calculator
+import xyz.javecs.tools.expr.Function
+
+class FunctionCallTest {
+    @Test fun func1() {
+        assertEquals(Double.NaN, Function("f(x,y)", arrayOf("x")).call(arrayOf(1.toDouble())))
+        assertEquals(Double.NaN, Function("f(x)", arrayOf("x")).call(arrayOf(1.toDouble(), 2.toDouble())))
+    }
+
+    @Test fun func2() {
+        val f = Function("f(x,y)", arrayOf("x * y"))
+        assertEquals(12.toDouble(), f.call(arrayOf(3.toDouble(), 4.toDouble())))
+        assertEquals(16.toDouble(), f.call(arrayOf(4.toDouble(), 4.toDouble())))
+    }
+
+    @Test fun func3() {
+        val f = Function("f(x,y)", arrayOf("max(x,y)"))
+        assertEquals(2.toDouble(), f.call(arrayOf(-1.toDouble(), 2.toDouble())))
+        assertEquals(0.toDouble(), f.call(arrayOf(-1.02, 0.toDouble())))
+    }
+
+    @Test fun func4() {
+        val f = Function("f(x,y,z)", arrayOf("a = x + y + z"))
+        assertEquals("f", f.name)
+        assertEquals(3, f.params.size)
+        assertEquals(5.toDouble(), f.call(arrayOf(1.toDouble(), 2.toDouble(), 2.toDouble())))
+    }
+
+    @Test fun func5() {
+        val f = Function("f(x,y,z)", arrayOf("a = x + y + z", "a = 0"))
+        assertEquals(0.toDouble(), f.call(arrayOf(1.toDouble(), 2.toDouble(), 2.toDouble())))
+    }
+
+    @Test fun func7() {
+        val f = Function("f()", arrayOf("100"))
+        assertEquals(100.toDouble(), f.call(emptyArray()))
+    }
+}
+

src/test/kotlin/xyz/javecs/tools/expr/test/kotlin/FunctionSignatureTest.kt

@@ -0,0 +1,50 @@
+package xyz.javecs.tools.expr.test.kotlin
+
+import kotlin.test.assertEquals
+import org.junit.Test
+import xyz.javecs.tools.expr.Calculator
+import xyz.javecs.tools.expr.Function
+import xyz.javecs.tools.expr.validate
+import kotlin.test.assertFails
+import kotlin.test.assertTrue
+
+class FunctionSignatureTest {
+    @Test fun signature1() {
+        val (name, params) = validate("f(x,y)")
+        assertEquals("f", name)
+        assertEquals("x", params[0])
+        assertEquals("y", params[1])
+    }
+
+    @Test fun signature2() {
+        val (name, params) = validate("f()")
+        assertEquals("f", name)
+        assertEquals(0, params.size)
+    }
+
+    @Test fun signature3() {
+        val (name, params) = validate("abc (     )")
+        assertEquals("abc", name)
+        assertEquals(0, params.size)
+    }
+
+    @Test fun signature4() {
+        val (name, params) = validate(" f123 ( abc , defh, d123456  )   ")
+        assertEquals("f123", name)
+        assertEquals("abc", params[0])
+        assertEquals("defh", params[1])
+        assertEquals("d123456", params[2])
+    }
+
+    @Test fun signature5() {
+        arrayOf(" f", "f*", "ffff(", "1()", "()", "(  a )").forEach {
+            try {
+                validate(it)
+                assertFails {  }
+            } catch (e: Exception) {
+                assertTrue { true }
+            }
+        }
+    }
+}
+