org.apache.flink.table.codegen.CodeFormatter.scala Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
package org.apache.flink.table.codegen
object CodeFormatter {
def format(code: String, maxLines: Int = -1): String = {
val strippedCode = stripExtraNewLines(code)
val formatter = new CodeFormatter
val lines = strippedCode.split("\n")
val needToTruncate = maxLines >= 0 && lines.length > maxLines
val filteredLines = if (needToTruncate) lines.take(maxLines) else lines
filteredLines.foreach(formatter.addLine)
if (needToTruncate) {
formatter.addLine(s"[truncated to $maxLines lines (total lines is ${lines.length})]")
}
formatter.result()
}
def stripExtraNewLines(input: String): String = {
val code = new StringBuilder
var lastLine: String = "dummy"
input.split('\n').foreach { l =>
val line = l.trim()
val skip = line == "" && (lastLine == "" || lastLine.endsWith("{") || lastLine.endsWith("*/"))
if (!skip) {
code.append(line)
code.append("\n")
}
lastLine = line
}
code.result()
}
}
private class CodeFormatter {
private val code = new StringBuilder
private val indentSize = 2
// Tracks the level of indentation in the current line.
private var indentLevel = 0
private var indentString = ""
private var currentLine = 1
// Tracks the level of indentation in multi-line comment blocks.
private var inCommentBlock = false
private var indentLevelOutsideCommentBlock = indentLevel
private def addLine(line: String): Unit = {
// We currently infer the level of indentation of a given line based on a simple heuristic that
// examines the number of parenthesis and braces in that line. This isn't the most robust
// implementation but works for all code that we generate.
val indentChange = line.count(c => "({".indexOf(c) >= 0) - line.count(c => ")}".indexOf(c) >= 0)
var newIndentLevel = math.max(0, indentLevel + indentChange)
// Please note that while we try to format the comment blocks in exactly the same way as the
// rest of the code, once the block ends, we reset the next line's indentation level to what it
// was immediately before entering the comment block.
if (!inCommentBlock) {
if (line.startsWith("/*")) {
// Handle multi-line comments
inCommentBlock = true
indentLevelOutsideCommentBlock = indentLevel
} else if (line.startsWith("//")) {
// Handle single line comments
newIndentLevel = indentLevel
}
}
if (inCommentBlock) {
if (line.endsWith("*/")) {
inCommentBlock = false
newIndentLevel = indentLevelOutsideCommentBlock
}
}
// Lines starting with '}' should be de-indented even if they contain '{' after;
// in addition, lines ending with ':' are typically labels
val thisLineIndent = if (line.startsWith("}") || line.startsWith(")") || line.endsWith(":")) {
" " * (indentSize * (indentLevel - 1))
} else {
indentString
}
code.append(f"/* ${currentLine}%03d */")
if (line.trim().length > 0) {
code.append(" ") // add a space after the line number comment.
code.append(thisLineIndent)
if (inCommentBlock && line.startsWith("*") || line.startsWith("*/")) code.append(" ")
code.append(line)
}
code.append("\n")
indentLevel = newIndentLevel
indentString = " " * (indentSize * newIndentLevel)
currentLine += 1
}
private def result(): String = code.result()
}