[spec] Implement schema coordinates

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/api.kt

@@ -114,6 +114,11 @@ fun String.parseAsGQLValue(options: ParserOptions = ParserOptions.Default): GQLR
   return parseInternal(null, options) { parseValue() }
 }
 
+@ApolloExperimental
+fun String.parseAsGQLSchemaCoordinate(options: ParserOptions = ParserOptions.Default): GQLResult<GQLSchemaCoordinate> {
+  return parseInternal(null, options) { parseSchemaCoordinate() }
+}
+
 fun String.toGQLValue(options: ParserOptions = ParserOptions.Default): GQLValue {
   return parseAsGQLValue(options).getOrThrow()
 }

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/gql.kt

@@ -2026,6 +2026,155 @@ enum class GQLDirectiveLocation {
   INPUT_FIELD_DEFINITION,
 }
 
+sealed interface GQLSchemaCoordinate
+
+class GQLTypeCoordinate(
+    override val sourceLocation: SourceLocation?,
+    val name: String,
+): GQLNode, GQLSchemaCoordinate {
+  override val children: List<GQLNode> = emptyList()
+
+  override fun writeInternal(writer: SDLWriter) {
+    writer.write(name)
+  }
+
+  fun copy(
+      sourceLocation: SourceLocation? = this.sourceLocation,
+      name: String = this.name
+  ): GQLTypeCoordinate {
+    return GQLTypeCoordinate(
+        sourceLocation,
+        name
+    )
+  }
+  override fun copyWithNewChildrenInternal(container: NodeContainer): GQLNode {
+    return copy()
+  }
+}
+
+class GQLDirectiveCoordinate(
+    override val sourceLocation: SourceLocation?,
+    val name: String,
+): GQLNode, GQLSchemaCoordinate {
+  override val children: List<GQLNode> = emptyList()
+
+  override fun writeInternal(writer: SDLWriter) {
+    writer.write("@")
+    writer.write(name)
+  }
+
+  fun copy(
+      sourceLocation: SourceLocation? = this.sourceLocation,
+      name: String = this.name
+  ): GQLDirectiveCoordinate {
+    return GQLDirectiveCoordinate(
+        sourceLocation,
+        name
+    )
+  }
+  override fun copyWithNewChildrenInternal(container: NodeContainer): GQLNode {
+    return copy()
+  }
+}
+
+class GQLMemberCoordinate(
+    override val sourceLocation: SourceLocation?,
+    val type: String,
+    val member: String
+): GQLNode, GQLSchemaCoordinate {
+  override val children: List<GQLNode> = emptyList()
+
+  override fun writeInternal(writer: SDLWriter) {
+    writer.write(type)
+    writer.write(".")
+    writer.write(member)
+  }
+
+  fun copy(
+      sourceLocation: SourceLocation? = this.sourceLocation,
+      type: String = this.type,
+      name: String = this.member
+  ): GQLMemberCoordinate {
+    return GQLMemberCoordinate(
+        sourceLocation,
+        type,
+        name
+    )
+  }
+
+  override fun copyWithNewChildrenInternal(container: NodeContainer): GQLNode {
+    return copy()
+  }
+}
+
+class GQLArgumentCoordinate(
+    override val sourceLocation: SourceLocation?,
+    val type: String,
+    val field: String,
+    val argument: String,
+): GQLNode, GQLSchemaCoordinate {
+  override val children: List<GQLNode> = emptyList()
+
+  override fun writeInternal(writer: SDLWriter) {
+    writer.write(type)
+    writer.write(".")
+    writer.write(field)
+    writer.write("(")
+    writer.write(argument)
+    writer.write(":)")
+  }
+
+  fun copy(
+      sourceLocation: SourceLocation? = this.sourceLocation,
+      type: String = this.type,
+      name: String = this.field,
+      argument: String = this.argument
+  ): GQLArgumentCoordinate {
+    return GQLArgumentCoordinate(
+        sourceLocation,
+        type,
+        name,
+        argument
+    )
+  }
+
+  override fun copyWithNewChildrenInternal(container: NodeContainer): GQLNode {
+    return copy()
+  }
+}
+
+class GQLDirectiveArgumentCoordinate(
+    override val sourceLocation: SourceLocation?,
+    val name: String,
+    val argument: String,
+): GQLNode, GQLSchemaCoordinate {
+  override val children: List<GQLNode> = emptyList()
+
+  override fun writeInternal(writer: SDLWriter) {
+    writer.write("@")
+    writer.write(name)
+    writer.write("(")
+    writer.write(argument)
+    writer.write(":)")
+  }
+
+  fun copy(
+      sourceLocation: SourceLocation? = this.sourceLocation,
+      name: String = this.name,
+      argument: String = this.argument
+  ): GQLDirectiveArgumentCoordinate {
+    return GQLDirectiveArgumentCoordinate(
+        sourceLocation,
+        name,
+        argument
+    )
+  }
+
+  override fun copyWithNewChildrenInternal(container: NodeContainer): GQLNode {
+    return copy()
+  }
+}
+
 
 @Suppress("UNCHECKED_CAST")
 class NodeContainer(nodes: List<GQLNode>) {

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/gqlcoordinate.kt

@@ -0,0 +1,80 @@
+package com.apollographql.apollo.ast
+
+import com.apollographql.apollo.annotations.ApolloExperimental
+
+fun resolveSchemaCoordinate(schema: Schema, coordinate: String): ResolvedSchemaElement? {
+  return resolveSchemaCoordinate(schema, coordinate.parseAsGQLSchemaCoordinate().getOrThrow())
+}
+
+sealed interface ResolvedSchemaElement
+
+class ResolvedType(val typeDefinition: GQLTypeDefinition) : ResolvedSchemaElement
+class ResolvedField(val fieldDefinition: GQLFieldDefinition) : ResolvedSchemaElement
+class ResolvedInputField(val inputField: GQLInputValueDefinition) : ResolvedSchemaElement
+class ResolvedEnumValue(val enumValue: GQLEnumValueDefinition) : ResolvedSchemaElement
+class ResolvedFieldArgument(val argument: GQLInputValueDefinition) : ResolvedSchemaElement
+class ResolvedDirective(val directiveDefinition: GQLDirectiveDefinition) : ResolvedSchemaElement
+class ResolvedDirectiveArgument(val argument: GQLInputValueDefinition) : ResolvedSchemaElement
+
+/**
+ * Resolves the given schema coordinate according to [schema].
+ *
+ * @return the [ResolvedSchemaElement] or `null` if not found.
+ *
+ * @throws IllegalArgumentException if any of the containing elements is not found or is of an unexpected type.
+ */
+@ApolloExperimental
+fun resolveSchemaCoordinate(schema: Schema, coordinate: GQLSchemaCoordinate): ResolvedSchemaElement? {
+  return when (coordinate) {
+    is GQLArgumentCoordinate -> {
+      val typeDefinition =
+        schema.typeDefinitions.get(coordinate.type) ?: throw IllegalArgumentException("Unknow type '${coordinate.type}'")
+
+      val fieldDefinition = when (typeDefinition) {
+        is GQLObjectTypeDefinition, is GQLInterfaceTypeDefinition -> {
+          typeDefinition.fieldDefinitions(schema).firstOrNull { it.name == coordinate.field }
+              ?: throw IllegalArgumentException("Unknow field '${coordinate.field}' in type '${typeDefinition.name}'")
+        }
+
+        else -> throw IllegalArgumentException("Expected '${typeDefinition.name}' to be an object or interface type")
+      }
+      fieldDefinition.arguments.firstOrNull { it.name == coordinate.argument }?.let { ResolvedFieldArgument(it) }
+    }
+
+    is GQLMemberCoordinate -> {
+      val typeDefinition =
+        schema.typeDefinitions.get(coordinate.type) ?: throw IllegalArgumentException("Unknow type '${coordinate.type}'")
+
+      when (typeDefinition) {
+        is GQLObjectTypeDefinition, is GQLInterfaceTypeDefinition -> {
+          typeDefinition.fieldDefinitions(schema).firstOrNull { it.name == coordinate.member }?.let { ResolvedField(it) }
+        }
+
+        is GQLInputObjectTypeDefinition -> {
+          typeDefinition.inputFields.firstOrNull { it.name == coordinate.member }?.let { ResolvedInputField(it) }
+        }
+
+        is GQLEnumTypeDefinition -> {
+          typeDefinition.enumValues.firstOrNull { it.name == coordinate.member }?.let { ResolvedEnumValue(it) }
+        }
+
+        else -> throw IllegalArgumentException("Expected '${typeDefinition.name}' to be an object, input object, interface or enum type")
+      }
+    }
+
+    is GQLTypeCoordinate -> {
+      schema.typeDefinitions.get(coordinate.name)?.let { ResolvedType(it) }
+    }
+
+    is GQLDirectiveArgumentCoordinate -> {
+      val directive =
+        schema.directiveDefinitions.get(coordinate.name) ?: throw IllegalArgumentException("Unknow directive '@${coordinate.name}'")
+
+      directive.arguments.firstOrNull { it.name == coordinate.argument }?.let { ResolvedDirectiveArgument(it) }
+    }
+
+    is GQLDirectiveCoordinate -> {
+      schema.directiveDefinitions.get(coordinate.name)?.let { ResolvedDirective(it) }
+    }
+  }
+}

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/gqltypedefinition.kt

@@ -2,6 +2,7 @@ package com.apollographql.apollo.ast
 
 import com.apollographql.apollo.annotations.ApolloInternal
 import com.apollographql.apollo.ast.Schema.Companion.NONNULL
+import kotlin.reflect.KClass
 
 // 5.5.2.3 Fragment spread is possible
 internal fun GQLTypeDefinition.sharesPossibleTypesWith(other: GQLTypeDefinition, schema: Schema): Boolean {
@@ -69,3 +70,16 @@ fun GQLTypeDefinition.canHaveKeyFields(): Boolean {
     else -> false
   }
 }
+
+
+internal fun KClass<out GQLTypeDefinition>.prettyName(): String {
+  return when (this) {
+    GQLObjectTypeDefinition::class -> "object"
+    GQLInterfaceTypeDefinition::class -> "interface"
+    GQLUnionTypeDefinition::class -> "union"
+    GQLEnumTypeDefinition::class -> "enum"
+    GQLScalarTypeDefinition::class -> "scalar"
+    GQLInputValueDefinition::class -> "input object"
+    else -> error("")
+  }
+}

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/internal/Lexer.kt

@@ -107,7 +107,9 @@ internal class Lexer(val src: String) {
         '(' -> return Token.LeftParenthesis(start, line, column(start))
         ')' -> return Token.RightParenthesis(start, line, column(start))
         '.' -> {
-          if (pos + 1 < len && src[pos] == '.' && src[pos + 1] == '.') {
+          if (pos == len || src[pos] != '.') {
+            return Token.Dot(start, line, column(start))
+          } else if (pos + 1 < len && src[pos] == '.' && src[pos + 1] == '.') {
             pos += 2
             return Token.Spread(start, line, column(start))
           } else {

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/internal/Parser.kt

@@ -1,9 +1,12 @@
 package com.apollographql.apollo.ast.internal
 
 import com.apollographql.apollo.ast.GQLArgument
+import com.apollographql.apollo.ast.GQLArgumentCoordinate
 import com.apollographql.apollo.ast.GQLBooleanValue
 import com.apollographql.apollo.ast.GQLDefinition
 import com.apollographql.apollo.ast.GQLDirective
+import com.apollographql.apollo.ast.GQLDirectiveArgumentCoordinate
+import com.apollographql.apollo.ast.GQLDirectiveCoordinate
 import com.apollographql.apollo.ast.GQLDirectiveDefinition
 import com.apollographql.apollo.ast.GQLDirectiveLocation
 import com.apollographql.apollo.ast.GQLDocument
@@ -25,6 +28,7 @@ import com.apollographql.apollo.ast.GQLInterfaceTypeDefinition
 import com.apollographql.apollo.ast.GQLInterfaceTypeExtension
 import com.apollographql.apollo.ast.GQLListType
 import com.apollographql.apollo.ast.GQLListValue
+import com.apollographql.apollo.ast.GQLMemberCoordinate
 import com.apollographql.apollo.ast.GQLNamedType
 import com.apollographql.apollo.ast.GQLNonNullType
 import com.apollographql.apollo.ast.GQLNullValue
@@ -36,11 +40,13 @@ import com.apollographql.apollo.ast.GQLOperationDefinition
 import com.apollographql.apollo.ast.GQLOperationTypeDefinition
 import com.apollographql.apollo.ast.GQLScalarTypeDefinition
 import com.apollographql.apollo.ast.GQLScalarTypeExtension
+import com.apollographql.apollo.ast.GQLSchemaCoordinate
 import com.apollographql.apollo.ast.GQLSchemaDefinition
 import com.apollographql.apollo.ast.GQLSchemaExtension
 import com.apollographql.apollo.ast.GQLSelection
 import com.apollographql.apollo.ast.GQLStringValue
 import com.apollographql.apollo.ast.GQLType
+import com.apollographql.apollo.ast.GQLTypeCoordinate
 import com.apollographql.apollo.ast.GQLTypeDefinition
 import com.apollographql.apollo.ast.GQLUnionTypeDefinition
 import com.apollographql.apollo.ast.GQLUnionTypeExtension
@@ -49,6 +55,7 @@ import com.apollographql.apollo.ast.GQLVariableDefinition
 import com.apollographql.apollo.ast.GQLVariableValue
 import com.apollographql.apollo.ast.ParserOptions
 import com.apollographql.apollo.ast.SourceLocation
+import kotlin.math.exp
 
 internal class Parser(
     src: String,
@@ -89,6 +96,10 @@ internal class Parser(
     return parseTopLevel(::parseTypeInternal)
   }
 
+  fun parseSchemaCoordinate(): GQLSchemaCoordinate {
+    return parseTopLevel(::parseSchemaCoordinateInternal)
+  }
+
   private fun advance() {
     lastToken = token
     if (lookaheadToken != null) {
@@ -980,6 +991,39 @@ internal class Parser(
     )
   }
 
+  private fun parseSchemaCoordinateInternal(): GQLSchemaCoordinate {
+    val sourceLocation = sourceLocation()
+    return if (token is Token.At) {
+      advance()
+      val name = expectToken<Token.Name>().value
+      if (token is Token.LeftParenthesis) {
+        advance()
+        val argument = expectToken<Token.Name>().value
+        expectToken<Token.Colon>()
+        expectToken<Token.RightParenthesis>()
+        GQLDirectiveArgumentCoordinate(sourceLocation, name, argument)
+      } else {
+        GQLDirectiveCoordinate(sourceLocation, name)
+      }
+    } else {
+      val name = expectToken<Token.Name>().value
+      if (token is Token.Dot) {
+        advance()
+        val member = expectToken<Token.Name>().value
+        if (token is Token.LeftParenthesis) {
+          advance()
+          val argument = expectToken<Token.Name>().value
+          expectToken<Token.Colon>()
+          expectToken<Token.RightParenthesis>()
+          GQLArgumentCoordinate(sourceLocation, name, member, argument)
+        } else {
+          GQLMemberCoordinate(sourceLocation, name, member)
+        }
+      } else {
+        GQLTypeCoordinate(sourceLocation, name)
+      }
+    }
+  }
   private fun parseTypeInternal(): GQLType {
     val start = token
 

libraries/apollo-ast/src/commonMain/kotlin/com/apollographql/apollo/ast/internal/Token.kt

@@ -90,4 +90,8 @@ internal sealed class Token(val start: kotlin.Int, val end: kotlin.Int, val line
   class String(start: kotlin.Int, end: kotlin.Int, line: kotlin.Int, column: kotlin.Int, val value: kotlin.String) : Token(start, end, line, column) {
     override fun toString() = "string: \"$value\""
   }
+
+  class Dot(start: kotlin.Int, line: kotlin.Int, column: kotlin.Int) : Token(start, start + 1, line, column) {
+    override fun toString() = "."
+  }
 }