Add Go language support.

build.gradle.kts

@@ -34,11 +34,13 @@ dependencies {
     testImplementation("junit:junit:4.13.2")
 
     intellijPlatform {
-        intellijIdeaCommunity("2025.1.4.1")
+        intellijIdeaCommunity("2025.2")
 
         bundledPlugin("com.intellij.java")
         bundledPlugin("org.jetbrains.kotlin")
         plugin("PythonCore", "252.23892.409")
+        plugin("org.jetbrains.plugins.go", "252.23892.360")
+        testPlugin("org.jetbrains.plugins.go", "252.23892.360")
 
         instrumentationTools()
         pluginVerifier()

src/main/kotlin/com/github/nikolaikopernik/codecomplexity/core/ComplexityInfoProvider.kt

@@ -11,7 +11,7 @@ import com.intellij.psi.PsiElement
 val PLUGIN_EP_NAME: ExtensionPointName<ComplexityInfoProvider> = ExtensionPointName("com.github.nikolaikopernik.codecomplexity.languageInfoProvider")
 val PLUGIN_HINT_KEY = SettingsKey<NoSettings>("code.complexity.hint")
 
-val SUPPORTED_LANGUAGES = setOf("java", "kotlin", "python")
+val SUPPORTED_LANGUAGES = setOf("java", "kotlin", "python", "go")
 
 /**
  * Main interface to calculate complexity for different languages.

src/main/kotlin/com/github/nikolaikopernik/codecomplexity/go/GoComplexityInfoProvider.kt

@@ -0,0 +1,95 @@
+package com.github.nikolaikopernik.codecomplexity.go
+
+import com.github.nikolaikopernik.codecomplexity.core.ComplexityInfoProvider
+import com.github.nikolaikopernik.codecomplexity.core.ComplexitySink
+import com.github.nikolaikopernik.codecomplexity.core.ElementVisitor
+import com.github.nikolaikopernik.codecomplexity.go.GoLanguageVisitor.Companion.isMemberFunction
+import com.github.nikolaikopernik.codecomplexity.go.GoLanguageVisitor.Companion.isToplevelVarDeclFunction
+import com.goide.GoLanguage
+import com.goide.psi.GoElement
+import com.goide.psi.GoFieldName
+import com.goide.psi.GoFunctionLit
+import com.goide.psi.GoFunctionOrMethodDeclaration
+import com.goide.psi.GoKey
+import com.goide.psi.GoValue
+import com.goide.psi.GoVarDefinition
+import com.goide.psi.GoVarSpec
+import com.intellij.lang.Language
+import com.intellij.psi.PsiElement
+
+class GoComplexityInfoProvider(override val language: Language = GoLanguage.INSTANCE) : ComplexityInfoProvider {
+
+    override fun getVisitor(sink: ComplexitySink): ElementVisitor = GoLanguageVisitor(sink)
+
+    override fun isComplexitySuitableMember(element: PsiElement): Boolean {
+        return element is GoFunctionOrMethodDeclaration || element is GoFunctionLit
+    }
+
+    override fun isClassWithBody(element: PsiElement): Boolean {
+        return false
+    }
+
+    override fun getNameElementFor(element: PsiElement): PsiElement {
+        return when (element) {
+            is GoFunctionOrMethodDeclaration -> element.nameIdentifier ?: element
+            is GoFunctionLit -> when {
+                element.isMemberFunction() -> element.memberFieldName ?: element
+                element.isToplevelVarDeclFunction() -> element.varDefinition ?: element
+                else -> element
+            }
+            else -> element
+        }
+    }
+}
+
+/**
+ * Retrieves the field name of a member function's associated field.
+ *
+ * This property is used to extract a field name corresponding to a member function within Go code.
+ * It navigates the PSI (Program Structure Interface) tree, analyzing the parent hierarchy of the
+ * `GoFunctionLit` instance and extracts the field name from the related `GoElement`.
+ *
+ * [GoFunctionLit] -<parent>-> [GoValue] -<parent>-> [GoElement] -<getKey>-> [GoKey] -<fieldName>-> [GoFieldName]
+ *
+ * If the field name cannot be resolved (e.g., the structure doesn't match the expected hierarchy),
+ * the property returns `null`.
+ *
+ * @return The trimmed field name of the associated field, or `null` if unavailable.
+ */
+val GoFunctionLit.memberFieldName: GoFieldName?
+    get() {
+        val goElement = this.parent?.parent as? GoElement ?: return null
+        return goElement.key?.fieldName
+    }
+
+val GoFunctionLit.memberFunctionFieldName: String?
+    get() {
+        val fieldName = this.memberFieldName ?: return null
+        return fieldName.text
+    }
+
+
+/**
+ * Retrieves the variable name associated with a Go function literal
+ * if it is used in the context of a variable declaration.
+ *
+ * This property queries the parent element of the function literal to determine if it is
+ * part of a `GoVarSpec`. If the parent is a variable specification, it extracts the first
+ * variable name from the list of variable definitions.
+ *
+ * [GoFunctionLit] -<parent>-> [GoVarSpec]
+ *
+ * @return The name of the variable associated with the function literal, or `null` if
+ * no variable declaration is found or the name cannot be determined.
+ */
+val GoFunctionLit.varDefinition: GoVarDefinition?
+    get() {
+        val goVarSpec = this.parent as? GoVarSpec ?: return null
+        return goVarSpec.varDefinitionList.firstOrNull()
+    }
+
+val GoFunctionLit.varFunctionVariableName: String?
+    get() {
+        val first = this.varDefinition ?: return null
+        return first.name
+    }