#315 Configurable indentation size.

diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/rules/files/IndentationRule.kt

@@ -46,7 +46,6 @@ import org.jetbrains.kotlin.utils.addToStdlib.firstNotNullResult
  */
 class IndentationRule(private val configRules: List<RulesConfig>) : Rule("indentation") {
     companion object {
-        const val INDENT_SIZE = 4
         private val increasingTokens = listOf(LPAR, LBRACE, LBRACKET)
         private val decreasingTokens = listOf(RPAR, RBRACE, RBRACKET)
     }
@@ -100,7 +99,7 @@ class IndentationRule(private val configRules: List<RulesConfig>) : Rule("indent
                 .apply { if (isEmpty()) return true }
                 .forEach {
                     WRONG_INDENTATION.warnAndFix(configRules, emitWarn, isFixMode, "tabs are not allowed for indentation", it.startOffset + it.text.indexOf('\t'), it) {
-                        (it as LeafPsiElement).replaceWithText(it.text.replace("\t", " ".repeat(INDENT_SIZE)))
+                        (it as LeafPsiElement).replaceWithText(it.text.replace("\t", " ".repeat(configuration.indentationSize)))
                     }
                 }
         return isFixMode  // true if we changed all tabs to spaces
@@ -128,7 +127,7 @@ class IndentationRule(private val configRules: List<RulesConfig>) : Rule("indent
      * Traverses the tree, keeping track of regular and exceptional indentations
      */
     private fun checkIndentation(node: ASTNode) {
-        val context = IndentContext()
+        val context = IndentContext(configuration)
         node.visit { astNode ->
             context.checkAndReset(astNode)
             if (astNode.elementType in increasingTokens) {
@@ -176,16 +175,16 @@ class IndentationRule(private val configRules: List<RulesConfig>) : Rule("indent
     /**
      * Class that contains state needed to calculate indent and keep track of exceptional indents
      */
-    private class IndentContext {
+    private class IndentContext(private val config: IndentationConfig) {
         private var regularIndent = 0
         private val exceptionalIndents = mutableListOf<ExceptionalIndent>()
 
         fun inc() {
-            regularIndent += INDENT_SIZE
+            regularIndent += config.indentationSize
         }
 
         fun dec() {
-            regularIndent -= INDENT_SIZE
+            regularIndent -= config.indentationSize
         }
 
         fun indent() = regularIndent + exceptionalIndents.sumBy { it.indent }

diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/utils/indentation/Checkers.kt

@@ -23,7 +23,6 @@ import com.pinterest.ktlint.core.ast.ElementType.VALUE_PARAMETER_LIST
 import com.pinterest.ktlint.core.ast.ElementType.WHITE_SPACE
 import com.pinterest.ktlint.core.ast.prevSibling
 import org.cqfn.diktat.ruleset.rules.files.IndentationError
-import org.cqfn.diktat.ruleset.rules.files.IndentationRule.Companion.INDENT_SIZE
 import org.cqfn.diktat.ruleset.rules.files.lastIndent
 import org.jetbrains.kotlin.com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.com.intellij.psi.PsiWhiteSpace
@@ -44,7 +43,7 @@ internal class AssignmentOperatorChecker(configuration: IndentationConfig) : Cus
         val prevNode = whiteSpace.prevSibling.node
         if (prevNode.elementType == EQ && prevNode.treeNext.let { it.elementType == WHITE_SPACE && it.textContains('\n') }) {
             return CheckResult.from(indentError.actual, (whiteSpace.parentIndent()
-                    ?: indentError.expected) + INDENT_SIZE, true)
+                    ?: indentError.expected) + configuration.indentationSize, true)
         }
         return null
     }
@@ -69,7 +68,7 @@ internal class ValueParameterListChecker(configuration: IndentationConfig) : Cus
                 // fixme: probably there is a better way to find column number
                 parameterList.parents().last().text.substringBefore(parameterAfterLpar.text).lines().last().count()
             } else if (parameterAfterLpar == null && configuration.extendedIndentOfParameters) {
-                indentError.expected + INDENT_SIZE
+                indentError.expected + configuration.indentationSize
             } else {
                 indentError.expected
             }
@@ -87,7 +86,7 @@ internal class ExpressionIndentationChecker(configuration: IndentationConfig) :
     override fun checkNode(whiteSpace: PsiWhiteSpace, indentError: IndentationError): CheckResult? {
         if (whiteSpace.parent.node.elementType == BINARY_EXPRESSION && whiteSpace.prevSibling.node.elementType == OPERATION_REFERENCE) {
             val expectedIndent = (whiteSpace.parentIndent() ?: indentError.expected) +
-                    (if (configuration.extendedIndentAfterOperators) 2 else 1) * INDENT_SIZE
+                    (if (configuration.extendedIndentAfterOperators) 2 else 1) * configuration.indentationSize
             return CheckResult.from(indentError.actual, expectedIndent)
         }
         return null
@@ -117,26 +116,26 @@ internal class SuperTypeListChecker(config: IndentationConfig) : CustomIndentati
         if (whiteSpace.nextSibling.node.elementType == SUPER_TYPE_LIST) {
             val hasNewlineBeforeColon = whiteSpace.node.prevSibling { it.elementType == COLON }!!
                     .treePrev.takeIf { it.elementType == WHITE_SPACE }?.textContains('\n') ?: false
-            val expectedIndent = indentError.expected + (if (hasNewlineBeforeColon) 2 else 1) * INDENT_SIZE
+            val expectedIndent = indentError.expected + (if (hasNewlineBeforeColon) 2 else 1) * configuration.indentationSize
             return CheckResult.from(indentError.actual, expectedIndent)
         } else if (whiteSpace.parent.node.elementType == SUPER_TYPE_LIST) {
-            val expectedIndent = whiteSpace.parentIndent() ?: (indentError.expected + INDENT_SIZE)
+            val expectedIndent = whiteSpace.parentIndent() ?: (indentError.expected + configuration.indentationSize)
             return CheckResult.from(indentError.actual, expectedIndent)
         }
         return null
     }
 }
 
 /**
- * This checker performs the following check: When dot call start on a new line, it should be indented by [INDENT_SIZE]
+ * This checker performs the following check: When dot call start on a new line, it should be indented by [IndentationConfig.indentationSize]
  */
 internal class DotCallChecker(config: IndentationConfig) : CustomIndentationChecker(config) {
     override fun checkNode(whiteSpace: PsiWhiteSpace, indentError: IndentationError): CheckResult? {
         whiteSpace.nextSibling.node.takeIf {
             it.elementType in listOf(DOT, SAFE_ACCESS) && it.treeNext.elementType in listOf(CALL_EXPRESSION, REFERENCE_EXPRESSION)
         }?.let {
             return CheckResult.from(indentError.actual, (whiteSpace.parentIndent()
-                    ?: indentError.expected) + INDENT_SIZE, true)
+                    ?: indentError.expected) + configuration.indentationSize, true)
         }
         return null
     }
@@ -157,7 +156,7 @@ internal class ConditionalsAndLoopsWithoutBracesChecker(config: IndentationConfi
                 .takeIf { it }
                 ?.let {
                     CheckResult.from(indentError.actual, (whiteSpace.parentIndent()
-                            ?: indentError.expected) + INDENT_SIZE, false)
+                            ?: indentError.expected) + configuration.indentationSize, false)
                 }
     }
 }

diktat-rules/src/main/kotlin/org/cqfn/diktat/ruleset/utils/indentation/IndentationConfig.kt

@@ -20,4 +20,9 @@ internal class IndentationConfig(config: Map<String, String>) : RuleConfiguratio
      * If true, if expression is split by newline after operator like +/-/`*`, then the next line is indented with two indentations instead of one
      */
     val extendedIndentAfterOperators = config["extendedIndentAfterOperators"]?.toBoolean() ?: true
+
+    /**
+     * The indentation size for each file
+     */
+    val indentationSize = config["indentationSize"]?.toInt() ?: 4
 }