blob: 38ca2c5fe2cd41808682d9ecab89185a2c6f0bf7 [file] [log] [blame]
// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/source/line_info.dart';
import '../scrape.dart';
/// Wire up [visitor] to [scrape] the given [path] containing [source] with
/// [info].
/// This is a top-level function instead of an instance method so that we can
/// hide it and not export it from scrape's public API. Only [Scrape] itself
/// should call this. We bind separately instead of passing these through the
/// [ScrapeVisitor] constructor so that subclasses of [ScrapeVisitor] don't
/// need to define a pass-through constructor.
void bindVisitor(ScrapeVisitor visitor, Scrape scrape, String path,
String source, LineInfo info) {
visitor._scrape = scrape;
visitor._path = path;
visitor._source = source;
visitor.lineInfo = info;
/// Base Visitor class with some utility functionality.
class ScrapeVisitor extends RecursiveAstVisitor<void> {
// These are initialized by [bindVisitor()].
late final Scrape _scrape;
late final String _path;
late final String _source;
late final LineInfo lineInfo;
/// How many levels deep the visitor is currently nested inside build methods.
int _inFlutterBuildMethods = 0;
String get path => _path;
// TODO(rnystrom): Remove this in favor of using surveyor for these kinds of
// analyses.
/// Whether the visitor is currently inside a Flutter "build" method,
/// either directly or nested inside some other function inside one.
/// This is only an approximate guess. It assumes a method is a "build"-like
/// method if it returns "Widget", or has a parameter list that starts with
/// "BuildContext context".
bool get isInFlutterBuildMethod => _inFlutterBuildMethods > 0;
bool _isBuildMethod(TypeAnnotation? returnType, SimpleIdentifier name,
FormalParameterList? parameters) {
var parameterString = parameters.toString();
if (returnType.toString() == 'void') return false;
if (parameterString.startsWith('(BuildContext context')) return true;
if (returnType.toString() == 'Widget') return true;
return false;
/// Add an occurrence of [item] to [histogram].
void record(String histogram, Object item) {
_scrape.record(histogram, item);
/// Write [message] to stdout, clearing the current line if needed.
void log(Object message) {
/// Print a nice representation of [node].
void printNode(AstNode node) {
/// Generate a nice string representation of [node] include file path and
/// line information.
String nodeToString(AstNode node) {
var startLine = lineInfo.getLocation(node.offset).lineNumber;
var endLine = lineInfo.getLocation(node.end).lineNumber;
startLine = startLine.clamp(0, lineInfo.lineCount - 1);
endLine = endLine.clamp(0, lineInfo.lineCount - 1);
var buffer = StringBuffer();
buffer.writeln('// $path:$startLine');
for (var line = startLine; line <= endLine; line++) {
// Note that getLocation() returns 1-based lines, but getOffsetOfLine()
// expects 0-based.
var offset = lineInfo.getOffsetOfLine(line - 1);
// -1 to not include the newline.
var end = lineInfo.getOffsetOfLine(line) - 1;
buffer.writeln(_source.substring(offset, end));
return buffer.toString();
/// Get the line number of the code at [offset].
int getLine(int offset) => lineInfo.getLocation(offset).lineNumber;
/// Override this to execute custom code before visiting a Flutter build
/// method.
void beforeVisitBuildMethod(Declaration node) {}
/// Override this to execute custom code after visiting a Flutter build
/// method.
void afterVisitBuildMethod(Declaration node) {}
void visitMethodDeclaration(MethodDeclaration node) {
var isBuild = _isBuildMethod(node.returnType,, node.parameters);
if (isBuild) _inFlutterBuildMethods++;
try {
if (isBuild) beforeVisitBuildMethod(node);
if (isBuild) afterVisitBuildMethod(node);
} finally {
if (isBuild) _inFlutterBuildMethods--;
void visitFunctionDeclaration(FunctionDeclaration node) {
var isBuild = _isBuildMethod(
node.returnType,, node.functionExpression.parameters);
if (isBuild) _inFlutterBuildMethods++;
try {
if (isBuild) beforeVisitBuildMethod(node);
if (isBuild) afterVisitBuildMethod(node);
} finally {
if (isBuild) _inFlutterBuildMethods--;