initial spike to show how KT-1565 might look for auto-escaping of HTML/XML/JSON/JDBC/URLs etc

libraries/stdlib/src/kotlin/template/HtmlTemplate.kt

@@ -0,0 +1,64 @@
+package kotlin.template
+
+import kotlin.dom.toXmlString
+import org.w3c.dom.Node
+
+
+/**
+ * Creates a string template from a string with $ expressions inside using HTML escaping of expressions.
+ */
+// TODO varargs on constructors seems to fail
+//class HtmlTemplate(vararg val text: String) {
+class HtmlTemplate(val constantText : Array<String>) {
+
+    /**
+     * Creates a builder of string expressions which use HTML encoding on expressions
+     */
+    fun builder() : HtmlTemplateBuilder {
+        // TODO we should allow the caller to pass these in when we create the builder!
+        val options = HtmlTemplateOptions()
+        return HtmlTemplateBuilder(constantText, options)
+    }
+}
+
+class HtmlTemplateOptions() {
+    var nullText : String = ""
+}
+
+open class HtmlTemplateBuilder(constantText : Array<String>, val options : HtmlTemplateOptions) : StringTemplateBuilder(constantText) {
+
+    override fun expression(expression : Any) : Unit {
+        val text = if (expression != null) expression.toString() ?: "" else options.nullText
+        escape(text)
+    }
+
+    /**
+     * Appends the DOM node, no HTML escaping is done as we assume its already escaped
+     */
+    fun expression(node : Node) : Unit {
+        // no need to escape
+        unescape(node.toXmlString(false))
+    }
+
+    /**
+     * Appends the given text escaped properly
+     */
+    fun escape(text : String): Unit {
+        appendNextConstant()
+        for (c in text) {
+            if (c == '<') buffer.append("&lt;")
+            else if (c == '>') buffer.append("&gt;")
+            else if (c == '&') buffer.append("&amp;")
+            else if (c == '"') buffer.append("&quot;")
+            else buffer.append(c)
+        }
+    }
+
+    /**
+     * Appends the unescaped text
+     */
+    fun unescape(text : String) {
+        appendNextConstant()
+        buffer.append(text)
+    }
+}

libraries/stdlib/src/kotlin/template/StringTemplate.kt

@@ -0,0 +1,44 @@
+package kotlin.template
+
+/**
+ * Creates a string template from a string with $ expressions inside.
+ */
+// TODO varargs on constructors seems to fail
+//class StringTemplate(vararg val text: String) {
+open class StringTemplate(val constantText : Array<String>) {
+
+    /**
+     * Creates a builder of string expressions
+     */
+    open fun builder() : StringTemplateBuilder = StringTemplateBuilder(constantText)
+}
+
+/**
+ * Used to build strings using expressions
+ */
+open class StringTemplateBuilder(val constantText : Array<String>){
+    protected val buffer: StringBuilder = StringBuilder()
+    var index : Int = 0
+
+    fun build() : String {
+        while (appendNextConstant()) {}
+        return buffer.toString() ?: ""
+    }
+
+    open fun expression(expression : Any) {
+        appendNextConstant()
+        buffer.append(expression)
+    }
+
+    /**
+     * Returns the next static text value from the template
+     */
+    protected fun appendNextConstant(): Boolean {
+        if (index < constantText.size) {
+            buffer.append(constantText[index++])
+            return true
+        } else {
+            return false
+        }
+    }
+}

libraries/testlib/test/template/HtmlTemplateTest.kt

@@ -0,0 +1,22 @@
+package test.template
+
+import junit.framework.TestCase
+import kotlin.template.*
+import kotlin.test.assertEquals
+
+class HtmlTemplateTest : TestCase() {
+    fun testTemplate(): Unit {
+        val foo = "James"
+        val bar = "x > 1"
+
+        // Code generated by the following template expression:
+        //
+        // val actual = [Html]"<h1>$foo</h1> <p>hey $bar</p>"
+        val builder = HtmlTemplate(array("<h1>", "</h1> <p>hey ", "</p>")).builder()
+        builder.expression(foo)
+        builder.expression(bar)
+        val actual = builder.build()
+
+        assertEquals("<h1>James</h1> <p>hey x &gt; 1</p>", actual)
+    }
+}

libraries/testlib/test/template/StringTemplateTest.kt

@@ -0,0 +1,20 @@
+package test.template
+
+import junit.framework.TestCase
+import kotlin.template.StringTemplate
+import kotlin.test.assertEquals
+
+class StringTemplateTest : TestCase() {
+    fun testTemplate(): Unit {
+        val name = "James"
+
+        // Code generated by the following template expression:
+        //
+        // val actual = "hello $name!"
+        val builder = StringTemplate(array("hello ", "!")).builder()
+        builder.expression(name)
+        val actual = builder.build()
+
+        assertEquals("hello James!", actual)
+    }
+}