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// Copyright 2016 The Tulsi Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import Foundation
/// Provides helper methods to extract meaningful error messages from Bazel stderr output.
struct BazelErrorExtractor {
static let DefaultErrors = 3
static func firstErrorLinesFromData(_ data: Data, maxErrors: Int = DefaultErrors) -> String? {
guard let stderr = NSString(data: data, encoding: String.Encoding.utf8.rawValue) else { return nil }
return firstErrorLinesFromString(stderr as String, maxErrors: maxErrors)
}
static func firstErrorLinesFromString(_ output: String, maxErrors: Int = DefaultErrors) -> String? {
func isNewLogMessage(_ line: String) -> Bool {
for newLogMessagePrefix in ["ERROR:", "INFO:", "WARNING:"] {
if line.hasPrefix(newLogMessagePrefix) {
return true
}
}
return false
}
var errorMessages = [String]()
var tracebackErrorMessages = Set<String>()
var activeTraceback = [String]()
for line in output.components(separatedBy: "\n") {
if !activeTraceback.isEmpty {
if isNewLogMessage(line) {
if !errorMessages.isEmpty {
let lastMessageIndex = errorMessages.count - 1
errorMessages[lastMessageIndex].append(activeTraceback.joined(separator: "\n"))
tracebackErrorMessages.insert(errorMessages[lastMessageIndex])
}
activeTraceback = []
} else {
activeTraceback.append(line)
}
} else if (line.hasPrefix("Traceback")) {
activeTraceback.append(line)
}
if (line.hasPrefix("ERROR:")) {
errorMessages.append(line)
}
}
if !activeTraceback.isEmpty && !errorMessages.isEmpty {
let lastMessageIndex = errorMessages.count - 1
errorMessages[lastMessageIndex].append(activeTraceback.joined(separator: "\n"))
tracebackErrorMessages.insert(errorMessages[lastMessageIndex])
}
// Display only up to 'maxErrors' number of errors to the user (including any
// associated traceback), but also check if any remaining errors include a traceback.
// Errors with a traceback should always be displayed regardless of how many errors are
// already being printed.
var errorSnippet = errorMessages.prefix(maxErrors).joined(separator: "\n")
tracebackErrorMessages.subtract(errorMessages.prefix(maxErrors))
errorSnippet.append(tracebackErrorMessages.joined(separator: "\n"))
if maxErrors < errorMessages.count {
errorSnippet += "\n..."
}
return errorSnippet
}
static func firstErrorLinesOrLastLinesFromString(_ output: String,
maxErrors: Int = DefaultErrors) -> String? {
if let errorLines = firstErrorLinesFromString(output, maxErrors: maxErrors) {
return errorLines
}
let errorLines = output.components(separatedBy: "\n").filter({ !$0.isEmpty })
let numErrorLinesToShow = min(errorLines.count, maxErrors)
var errorSnippet = errorLines.suffix(numErrorLinesToShow).joined(separator: "\n")
if numErrorLinesToShow < errorLines.count {
errorSnippet = "...\n" + errorSnippet
}
return errorSnippet
}
private init() {
}
}