kotlincursor.processor.KCursorDataClass.kt Maven / Gradle / Ivy

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Kotlin Cursor & ContentValues boilerplate annotation processor.
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package kotlincursor.processor

import com.squareup.kotlinpoet.ClassName
import com.squareup.kotlinpoet.CodeBlock
import com.squareup.kotlinpoet.FunSpec
import com.squareup.kotlinpoet.KotlinFile
import com.squareup.kotlinpoet.TypeName
import javax.annotation.processing.Messager
import javax.lang.model.element.ElementKind
import javax.lang.model.element.Modifier
import javax.lang.model.element.TypeElement
import javax.lang.model.element.VariableElement
import javax.lang.model.util.Elements
import javax.lang.model.util.Types
import javax.tools.Diagnostic

class KCursorDataClass(
        val messager: Messager,
        val elements: Elements,
        val types: Types

) {
    fun generateKotlinFile(classElement: TypeElement): KotlinFile {
        val packageName = elements.getPackageOf(classElement).qualifiedName.toString()
        val fileName = CLASS_FILE_PREFIX + classElement.simpleName.toString()

        val properties = classElement.enclosedElements
                .filter { it.kind == ElementKind.FIELD
                        && !it.modifiers.contains(Modifier.STATIC)
                        && it is VariableElement }
                .map { ColumnProperty(it as VariableElement) }

        return KotlinFile.builder(packageName, fileName)
                .addFun(generateToContentValuesMethod(classElement, properties))
                .addFun(generateFromCursorMethod(classElement, properties))
                .build()
    }

    private fun generateToContentValuesMethod(classElement: TypeElement, properties: List): FunSpec {
        val methodBuilder = FunSpec.builder("toContentValues")
                .receiver(TypeName.get(classElement.asType()))
                .addStatement("val values = $CONTENT_VALUES()")
                .returns(CONTENT_VALUES)

        properties.forEach {
            val columnAdapter = it.columnAdapter
            if (columnAdapter != null) {
                if (it.isNullable) methodBuilder.addCode("if (${it.humanName} != null) ")
                methodBuilder.addStatement(
                        "%L().toContentValues(values, \"${it.columnName}\", ${it.humanName})",
                        columnAdapter)
            } else if (it.isSupportedType) {
                methodBuilder.addStatement(
                        "values.put(\"${it.columnName}\", ${it.humanName})")
            } else if (it.isColumnTypeCursorDataClass(types)) {
                if (it.isNullable) methodBuilder.addCode("if (${it.humanName} != null) ")
                methodBuilder.addStatement(
                        "values.putAll(${it.humanName}.toContentValues())")
            } else {
                messager.printMessage(Diagnostic.Kind.ERROR, "Property \"${it.humanName}\" " +
                        "of type ${it.columnType} can't be converted to ContentValues.",
                        it.element)
            }
        }
        return methodBuilder.addStatement("return values").build()
    }

    private fun generateFromCursorMethod(classElement: TypeElement, properties: List): FunSpec {
        val methodBuilder = FunSpec.builder("to${classElement.simpleName}")
                .receiver(CURSOR)
                .returns(TypeName.get(classElement.asType()))

        val names = properties.map { it.humanName }
        properties.forEach {
            val columnAdapter = it.columnAdapter
            if (columnAdapter != null) {
                methodBuilder.addStatement(
                        "val ${it.humanName} = %L().fromCursor(this, \"${it.columnName}\")",
                        columnAdapter)
            } else if (it.isSupportedType) {
                if (it.isNullable) {
                    methodBuilder.addCode(generateReadNullableProperty(it))
                } else {
                    methodBuilder.addCode(generateReadProperty(it))
                }
            } else if (it.isColumnTypeCursorDataClass(types)) {
                val columnTypeSimpleName = types.asElement(it.element.asType()).simpleName
                methodBuilder.addStatement(
                        "val ${it.humanName} = this.to$columnTypeSimpleName()"
                )
            } else {
                messager.printMessage(Diagnostic.Kind.ERROR, "Property \"${it.humanName}\" " +
                        "of type ${it.columnType} can't be converted from Cursor.",
                        it.element)
            }
        }
        val constructorCallBlock = generateClassConstructorCall(classElement.simpleName.toString(), names)
        return methodBuilder.addStatement("return $constructorCallBlock").build()
    }

    private fun generateReadNullableProperty(property: ColumnProperty): CodeBlock {
        val columnIndexVariableName = "${property.humanName}Index"
        val getValueBlock = CodeBlock.of(property.getCursorMethod(), columnIndexVariableName)
        val nullCheckBlock = CodeBlock.of(
                "if ($columnIndexVariableName == -1 || this.isNull($columnIndexVariableName)) null else %L",
                getValueBlock)
        return CodeBlock.builder()
                .addStatement("val $columnIndexVariableName = this.getColumnIndex(\"${property.columnName}\")")
                .addStatement("val ${property.humanName} = %L", nullCheckBlock)
                .build()
    }

    private fun generateReadProperty(property: ColumnProperty): CodeBlock {
        val getColumnIndexOrThrowBlock = CodeBlock.of("this.getColumnIndexOrThrow(\"${property.columnName}\")")
        val getValueBlock = CodeBlock.of(property.getCursorMethod(), getColumnIndexOrThrowBlock)
        return CodeBlock.builder()
                .addStatement("val ${property.humanName} = %L", getValueBlock)
                .build()
    }

    private fun generateClassConstructorCall(className: String, names: List): String {
        return "$className(${names.joinToString()})"
    }

    companion object {
        const val CLASS_FILE_PREFIX = "KCursor"

        val CONTENT_VALUES = ClassName.get("android.content", "ContentValues")
        val CURSOR = ClassName.get("android.database", "Cursor")
    }
}