split up babel core into multiple modules

packages/babel-traverse/src/path/inference/inferer-reference.js

@@ -0,0 +1,211 @@
+import * as t from "babel-types";
+
+/**
+ * [Please add a description.]
+ */
+
+export default function (node) {
+  if (!this.isReferenced()) return;
+
+  // check if a binding exists of this value and if so then return a union type of all
+  // possible types that the binding could be
+  var binding = this.scope.getBinding(node.name);
+  if (binding) {
+    if (binding.identifier.typeAnnotation) {
+      return binding.identifier.typeAnnotation;
+    } else {
+      return getTypeAnnotationBindingConstantViolations(this, node.name);
+    }
+  }
+
+  // built-in values
+  if (node.name === "undefined") {
+    return t.voidTypeAnnotation();
+  } else if (node.name === "NaN" || node.name === "Infinity") {
+    return t.numberTypeAnnotation();
+  } else if (node.name === "arguments") {
+    // todo
+  }
+}
+
+/**
+ * [Please add a description.]
+ */
+
+function getTypeAnnotationBindingConstantViolations(path, name) {
+  var binding = path.scope.getBinding(name);
+
+  var types = [];
+  path.typeAnnotation = t.unionTypeAnnotation(types);
+
+  var functionConstantViolations = [];
+  var constantViolations = getConstantViolationsBefore(binding, path, functionConstantViolations);
+
+  var testType = getConditionalAnnotation(path, name);
+  if (testType) {
+    var testConstantViolations = getConstantViolationsBefore(binding, testType.ifStatement);
+
+    // remove constant violations observed before the IfStatement
+    constantViolations = constantViolations.filter((path) => testConstantViolations.indexOf(path) < 0);
+
+    // clear current types and add in observed test type
+    types.push(testType.typeAnnotation);
+  }
+
+  if (constantViolations.length) {
+    // pick one constant from each scope which will represent the last possible
+    // control flow path that it could've taken/been
+    var rawConstantViolations = constantViolations.reverse();
+    var visitedScopes = [];
+    constantViolations = [];
+    for (let violation of (rawConstantViolations: Array)) {
+      var violationScope = violation.scope;
+      if (visitedScopes.indexOf(violationScope) >= 0) continue;
+
+      visitedScopes.push(violationScope);
+      constantViolations.push(violation);
+
+      if (violationScope === path.scope) {
+        constantViolations = [violation];
+        break;
+      }
+    }
+
+    // add back on function constant violations since we can't track calls
+    constantViolations = constantViolations.concat(functionConstantViolations);
+
+    // push on inferred types of violated paths
+    for (let violation of (constantViolations: Array)) {
+      types.push(violation.getTypeAnnotation());
+    }
+  }
+
+  if (types.length) {
+    return t.createUnionTypeAnnotation(types);
+  }
+}
+
+/**
+ * [Please add a description.]
+ */
+
+function getConstantViolationsBefore(binding, path, functions) {
+  var violations = binding.constantViolations.slice();
+  violations.unshift(binding.path);
+  return violations.filter((violation) => {
+    violation = violation.resolve();
+    var status = violation._guessExecutionStatusRelativeTo(path);
+    if (functions && status === "function") functions.push(violation);
+    return status === "before";
+  });
+}
+
+/**
+ * [Please add a description.]
+ */
+
+function inferAnnotationFromBinaryExpression(name, path) {
+  var operator = path.node.operator;
+
+  var right = path.get("right").resolve();
+  var left  = path.get("left").resolve();
+
+  var target;
+  if (left.isIdentifier({ name })) {
+    target = right;
+  } else if (right.isIdentifier({ name })) {
+    target = left;
+  }
+  if (target) {
+    if (operator === "===") {
+      return target.getTypeAnnotation();
+    } else if (t.BOOLEAN_NUMBER_BINARY_OPERATORS.indexOf(operator) >= 0) {
+      return t.numberTypeAnnotation();
+    } else {
+      return;
+    }
+  } else {
+    if (operator !== "===") return;
+  }
+
+  //
+  var typeofPath;
+  var typePath;
+  if (left.isUnaryExpression({ operator: "typeof" })) {
+    typeofPath = left;
+    typePath = right;
+  } else if (right.isUnaryExpression({ operator: "typeof" })) {
+    typeofPath = right;
+    typePath = left;
+  }
+  if (!typePath && !typeofPath) return;
+
+  // ensure that the type path is a Literal
+  typePath = typePath.resolve();
+  if (!typePath.isLiteral()) return;
+
+  // and that it's a string so we can infer it
+  var typeValue = typePath.node.value;
+  if (typeof typeValue !== "string") return;
+
+  // and that the argument of the typeof path references us!
+  if (!typeofPath.get("argument").isIdentifier({ name })) return;
+
+  // turn type value into a type annotation
+  return t.createTypeAnnotationBasedOnTypeof(typePath.node.value);
+}
+
+/**
+ * [Please add a description.]
+ */
+
+function getParentConditionalPath(path) {
+  var parentPath;
+  while (parentPath = path.parentPath) {
+    if (parentPath.isIfStatement() || parentPath.isConditionalExpression()) {
+      if (path.key === "test") {
+        return;
+      } else {
+        return parentPath;
+      }
+    } else {
+      path = parentPath;
+    }
+  }
+}
+
+/**
+ * [Please add a description.]
+ */
+
+function getConditionalAnnotation(path, name) {
+  var ifStatement = getParentConditionalPath(path);
+  if (!ifStatement) return;
+
+  var test  = ifStatement.get("test");
+  var paths = [test];
+  var types = [];
+
+  do {
+    let path = paths.shift().resolve();
+
+    if (path.isLogicalExpression()) {
+      paths.push(path.get("left"));
+      paths.push(path.get("right"));
+    }
+
+    if (path.isBinaryExpression()) {
+      var type = inferAnnotationFromBinaryExpression(name, path);
+      if (type) types.push(type);
+    }
+  } while(paths.length);
+
+  if (types.length) {
+    return {
+      typeAnnotation: t.createUnionTypeAnnotation(types),
+      ifStatement
+    };
+  } else {
+    return getConditionalAnnotation(ifStatement, name);
+  }
+}