Throw exception for `String + CSSSelector` with `self` cases. (#1462)

* Throw exception for `String + CSSSelector` with `self` cases.

* Refactoring: CSSSelector: open -> abstract, assertTrue -> assertFailsWith

* Exceptions rewording

* CSSSelfSelector: public -> internal

web/core/src/jsMain/kotlin/org/jetbrains/compose/web/css/CSSRules.kt

@@ -22,7 +22,7 @@ data class CSSStyleRuleDeclaration(
     override val style: StyleHolder
 ) : CSSRuleDeclaration, CSSStyledRuleDeclaration {
     override val header
-        get() = selector.toString()
+        get() = selector.asString()
 }
 
 interface CSSGroupingRuleDeclaration: CSSRuleDeclaration {

web/core/src/jsMain/kotlin/org/jetbrains/compose/web/css/StyleSheet.kt

@@ -79,8 +79,9 @@ open class StyleSheet(
     }
 
     @Suppress("EqualsOrHashCode")
-    class CSSSelfSelector(var selector: CSSSelector? = null) : CSSSelector() {
+    internal class CSSSelfSelector(var selector: CSSSelector? = null) : CSSSelector() {
-        override fun toString(): String = selector.toString()
+        override fun toString(): String = throw IllegalStateException("You can't concatenate `String + CSSSelector` which contains `self` or `root`. Use `selector(<your string>)` to convert `String` to `CSSSelector` for proper work. https://github.com/JetBrains/compose-jb/issues/1440")
+        override fun asString(): String = selector?.asString() ?: throw IllegalStateException("You can't instantiate self")
         override fun equals(other: Any?): Boolean {
             return other is CSSSelfSelector
         }
@@ -157,7 +158,12 @@ fun buildCSS(
     cssRule: CSSBuilder.() -> Unit
 ): Pair<StyleHolder, CSSRuleDeclarationList> {
     val styleSheet = StyleSheetBuilderImpl()
-    val builder = CSSBuilderImpl(thisClass, thisContext, styleSheet)
+    // workaround because of problems with plus operator overloading
+    val root = if (thisClass is StyleSheet.CSSSelfSelector) thisClass else StyleSheet.CSSSelfSelector(thisClass)
+    // workaround because of problems with plus operator overloading
+    val self = if (thisContext is StyleSheet.CSSSelfSelector) thisContext else StyleSheet.CSSSelfSelector(thisContext)
+
+    val builder = CSSBuilderImpl(root, self, styleSheet)
     builder.cssRule()
     return builder to styleSheet.cssRules
 }

web/core/src/jsMain/kotlin/org/jetbrains/compose/web/css/selectors/CSSSelectors.kt

@@ -21,15 +21,20 @@ sealed class Nth {
     }
 }
 
-open class CSSSelector {
+abstract class CSSSelector {
     override fun equals(other: Any?): Boolean {
-        return this === other || toString() == other.toString()
+        return this === other || asString() == (other as? CSSSelector)?.asString()
     }
 
     internal open fun contains(other: CSSSelector, strict: Boolean = false): Boolean {
         return if (strict) this === other else this == other
     }
 
+    // This method made for workaround because of possible concatenation of `String + CSSSelector`,
+    // so `toString` is called for such operator, but we are calling `asString` for instantiation.
+    // `toString` is reloaded for CSSSelfSelector
+    internal open fun asString(): String = toString()
+
     data class Raw(val selector: String) : CSSSelector() {
         override fun toString(): String = selector
     }
@@ -77,6 +82,7 @@ open class CSSSelector {
             contains(this, other, selectors, strict)
 
         override fun toString(): String = selectors.joinToString("")
+        override fun asString(): String = selectors.joinToString("") { it.asString() }
     }
 
     data class Group(val selectors: List<CSSSelector>) : CSSSelector() {
@@ -84,6 +90,7 @@ open class CSSSelector {
             contains(this, other, selectors, strict)
 
         override fun toString(): String = selectors.joinToString(", ")
+        override fun asString(): String = selectors.joinToString(", ") { it.asString() }
     }
 
     data class Descendant(val parent: CSSSelector, val selected: CSSSelector) : CSSSelector() {
@@ -91,6 +98,7 @@ open class CSSSelector {
             contains(this, other, listOf(parent, selected), strict)
 
         override fun toString(): String = "$parent $selected"
+        override fun asString(): String = "${parent.asString()} ${selected.asString()}"
     }
 
     data class Child(val parent: CSSSelector, val selected: CSSSelector) : CSSSelector() {
@@ -98,6 +106,7 @@ open class CSSSelector {
             contains(this, other, listOf(parent, selected), strict)
 
         override fun toString(): String = "$parent > $selected"
+        override fun asString(): String = "${parent.asString()} > ${selected.asString()}"
     }
 
     data class Sibling(val prev: CSSSelector, val selected: CSSSelector) : CSSSelector() {
@@ -105,6 +114,7 @@ open class CSSSelector {
             contains(this, other, listOf(prev, selected), strict)
 
         override fun toString(): String = "$prev ~ $selected"
+        override fun asString(): String = "${prev.asString()} ~ ${selected.asString()}"
     }
 
     data class Adjacent(val prev: CSSSelector, val selected: CSSSelector) : CSSSelector() {
@@ -112,6 +122,7 @@ open class CSSSelector {
             contains(this, other, listOf(prev, selected), strict)
 
         override fun toString(): String = "$prev + $selected"
+        override fun asString(): String = "${prev.asString()} + ${selected.asString()}"
     }
 
     open class PseudoClass(val name: String) : CSSSelector() {
@@ -202,7 +213,7 @@ open class CSSSelector {
             override fun contains(other: CSSSelector, strict: Boolean): Boolean =
                 contains(this, other, listOf(selector), strict)
 
-            override fun argsStr() = "$selector"
+            override fun argsStr() = "${selector.asString()}"
         }
 
         // Etc
@@ -238,7 +249,7 @@ open class CSSSelector {
             override fun contains(other: CSSSelector, strict: Boolean): Boolean =
                 contains(this, other, listOf(selector), strict)
 
-            override fun argsStr() = selector.toString()
+            override fun argsStr() = selector.asString()
         }
     }
 }
@@ -246,16 +257,11 @@ open class CSSSelector {
 fun selector(selector: String) = CSSSelector.Raw(selector)
 fun combine(vararg selectors: CSSSelector) = CSSSelector.Combine(selectors.toMutableList())
 operator fun CSSSelector.plus(selector: CSSSelector) = combine(this, selector)
-operator fun String.plus(selector: CSSSelector) = combine(selector(this), selector)
 operator fun CSSSelector.plus(selector: String) = combine(this, selector(selector))
 operator fun CSSSelector.plus(selector: CSSSelector.Combine): CSSSelector.Combine {
     selector.selectors.add(0, this)
     return selector
 }
-operator fun String.plus(selector: CSSSelector.Combine): CSSSelector.Combine {
-    selector.selectors.add(0, selector(this))
-    return selector
-}
 operator fun CSSSelector.Combine.plus(selector: CSSSelector): CSSSelector.Combine {
     this.selectors.add(selector)
     return this

web/core/src/jsTest/kotlin/CSSStylesheetTests.kt

@@ -13,10 +13,8 @@ import org.jetbrains.compose.web.dom.Div
 import org.jetbrains.compose.web.dom.stringPresentation
 import org.w3c.dom.HTMLElement
 import org.w3c.dom.get
-import kotlin.test.Test
-import kotlin.test.assertEquals
 import org.jetbrains.compose.web.testutils.*
-import kotlin.test.assertContains
+import kotlin.test.*
 
 object AppCSSVariables {
     val width by variable<CSSUnitValue>()
@@ -311,4 +309,17 @@ class CSSVariableTests {
             "Sibling selector isn't generated correctly"
         )
     }
+
+    @Test
+    fun testStringPlusCSSSelectorConcatenation() {
+        assertFailsWith<IllegalStateException>("Concatenation of String + CSSSelector should be restricted.") {
+            object : StyleSheet() {
+                val myClass by style {
+                    ("h1" + self) {
+                        color(Color.green)
+                    }
+                }
+            }
+        }
+    }
 }