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node_modules/graphql/utilities/valueFromAST.js.flow

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+// @flow strict
+
+import objectValues from '../polyfills/objectValues';
+
+import keyMap from '../jsutils/keyMap';
+import inspect from '../jsutils/inspect';
+import invariant from '../jsutils/invariant';
+import isInvalid from '../jsutils/isInvalid';
+import { type ObjMap } from '../jsutils/ObjMap';
+
+import { Kind } from '../language/kinds';
+import { type ValueNode } from '../language/ast';
+
+import {
+  type GraphQLInputType,
+  isScalarType,
+  isEnumType,
+  isInputObjectType,
+  isListType,
+  isNonNullType,
+} from '../type/definition';
+
+/**
+ * Produces a JavaScript value given a GraphQL Value AST.
+ *
+ * A GraphQL type must be provided, which will be used to interpret different
+ * GraphQL Value literals.
+ *
+ * Returns `undefined` when the value could not be validly coerced according to
+ * the provided type.
+ *
+ * | GraphQL Value        | JSON Value    |
+ * | -------------------- | ------------- |
+ * | Input Object         | Object        |
+ * | List                 | Array         |
+ * | Boolean              | Boolean       |
+ * | String               | String        |
+ * | Int / Float          | Number        |
+ * | Enum Value           | Mixed         |
+ * | NullValue            | null          |
+ *
+ */
+export function valueFromAST(
+  valueNode: ?ValueNode,
+  type: GraphQLInputType,
+  variables?: ?ObjMap<mixed>,
+): mixed | void {
+  if (!valueNode) {
+    // When there is no node, then there is also no value.
+    // Importantly, this is different from returning the value null.
+    return;
+  }
+
+  if (isNonNullType(type)) {
+    if (valueNode.kind === Kind.NULL) {
+      return; // Invalid: intentionally return no value.
+    }
+    return valueFromAST(valueNode, type.ofType, variables);
+  }
+
+  if (valueNode.kind === Kind.NULL) {
+    // This is explicitly returning the value null.
+    return null;
+  }
+
+  if (valueNode.kind === Kind.VARIABLE) {
+    const variableName = valueNode.name.value;
+    if (!variables || isInvalid(variables[variableName])) {
+      // No valid return value.
+      return;
+    }
+    const variableValue = variables[variableName];
+    if (variableValue === null && isNonNullType(type)) {
+      return; // Invalid: intentionally return no value.
+    }
+    // Note: This does no further checking that this variable is correct.
+    // This assumes that this query has been validated and the variable
+    // usage here is of the correct type.
+    return variableValue;
+  }
+
+  if (isListType(type)) {
+    const itemType = type.ofType;
+    if (valueNode.kind === Kind.LIST) {
+      const coercedValues = [];
+      for (const itemNode of valueNode.values) {
+        if (isMissingVariable(itemNode, variables)) {
+          // If an array contains a missing variable, it is either coerced to
+          // null or if the item type is non-null, it considered invalid.
+          if (isNonNullType(itemType)) {
+            return; // Invalid: intentionally return no value.
+          }
+          coercedValues.push(null);
+        } else {
+          const itemValue = valueFromAST(itemNode, itemType, variables);
+          if (isInvalid(itemValue)) {
+            return; // Invalid: intentionally return no value.
+          }
+          coercedValues.push(itemValue);
+        }
+      }
+      return coercedValues;
+    }
+    const coercedValue = valueFromAST(valueNode, itemType, variables);
+    if (isInvalid(coercedValue)) {
+      return; // Invalid: intentionally return no value.
+    }
+    return [coercedValue];
+  }
+
+  if (isInputObjectType(type)) {
+    if (valueNode.kind !== Kind.OBJECT) {
+      return; // Invalid: intentionally return no value.
+    }
+    const coercedObj = Object.create(null);
+    const fieldNodes = keyMap(valueNode.fields, field => field.name.value);
+    for (const field of objectValues(type.getFields())) {
+      const fieldNode = fieldNodes[field.name];
+      if (!fieldNode || isMissingVariable(fieldNode.value, variables)) {
+        if (field.defaultValue !== undefined) {
+          coercedObj[field.name] = field.defaultValue;
+        } else if (isNonNullType(field.type)) {
+          return; // Invalid: intentionally return no value.
+        }
+        continue;
+      }
+      const fieldValue = valueFromAST(fieldNode.value, field.type, variables);
+      if (isInvalid(fieldValue)) {
+        return; // Invalid: intentionally return no value.
+      }
+      coercedObj[field.name] = fieldValue;
+    }
+    return coercedObj;
+  }
+
+  if (isEnumType(type)) {
+    if (valueNode.kind !== Kind.ENUM) {
+      return; // Invalid: intentionally return no value.
+    }
+    const enumValue = type.getValue(valueNode.value);
+    if (!enumValue) {
+      return; // Invalid: intentionally return no value.
+    }
+    return enumValue.value;
+  }
+
+  if (isScalarType(type)) {
+    // Scalars fulfill parsing a literal value via parseLiteral().
+    // Invalid values represent a failure to parse correctly, in which case
+    // no value is returned.
+    let result;
+    try {
+      result = type.parseLiteral(valueNode, variables);
+    } catch (_error) {
+      return; // Invalid: intentionally return no value.
+    }
+    if (isInvalid(result)) {
+      return; // Invalid: intentionally return no value.
+    }
+    return result;
+  }
+
+  // Not reachable. All possible input types have been considered.
+  invariant(false, 'Unexpected input type: ' + inspect((type: empty)));
+}
+
+// Returns true if the provided valueNode is a variable which is not defined
+// in the set of variables.
+function isMissingVariable(valueNode, variables) {
+  return (
+    valueNode.kind === Kind.VARIABLE &&
+    (!variables || isInvalid(variables[valueNode.name.value]))
+  );
+}