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Improve printing of strings #22945

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e2c4ec1
Improve printing of strings
som-snytt Apr 9, 2025
9f19b05
Improve SourceCode string printing
som-snytt Apr 9, 2025
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76 changes: 62 additions & 14 deletions compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@ import scala.annotation.switch
import config.{Config, Feature}
import cc.*

import java.lang.StringBuilder

class PlainPrinter(_ctx: Context) extends Printer {

/** The context of all public methods in Printer and subclasses.
Expand Down Expand Up @@ -668,22 +670,18 @@ class PlainPrinter(_ctx: Context) extends Printer {

def toText(denot: Denotation): Text = toText(denot.symbol) ~ "/D"

private def escapedChar(ch: Char): String = (ch: @switch) match {
case '\b' => "\\b"
case '\t' => "\\t"
case '\n' => "\\n"
case '\f' => "\\f"
case '\r' => "\\r"
case '"' => "\\\""
case '\'' => "\\\'"
case '\\' => "\\\\"
case _ => if ch.isControl then f"${"\\"}u${ch.toInt}%04x" else String.valueOf(ch).nn
}
private def escapedChar(ch: Char): String =
if requiresFormat(ch) then
val b = StringBuilder().append('\'')
escapedChar(b, ch)
b.append('\'').toString
else
"'" + ch + "'"

def toText(const: Constant): Text = const.tag match {
case StringTag => stringText("\"" + escapedString(const.value.toString) + "\"")
case StringTag => stringText(escapedString(const.value.toString, quoted = true))
case ClazzTag => "classOf[" ~ toText(const.typeValue) ~ "]"
case CharTag => literalText(s"'${escapedChar(const.charValue)}'")
case CharTag => literalText(escapedChar(const.charValue))
case LongTag => literalText(const.longValue.toString + "L")
case DoubleTag => literalText(const.doubleValue.toString + "d")
case FloatTag => literalText(const.floatValue.toString + "f")
Expand All @@ -701,7 +699,57 @@ class PlainPrinter(_ctx: Context) extends Printer {
~ (if param.isTypeParam then "" else ": ")
~ toText(param.paramInfo)

protected def escapedString(str: String): String = str flatMap escapedChar
protected final def escapedString(str: String): String = escapedString(str, quoted = false)

private def requiresFormat(c: Char): Boolean = (c: @switch) match
case '\b' | '\t' | '\n' | '\f' | '\r' | '"' | '\'' | '\\' => true
case c => c.isControl

private def escapedString(text: String, quoted: Boolean): String =
def mustBuild: Boolean =
var i = 0
while i < text.length do
if requiresFormat(text.charAt(i)) then return true
i += 1
false
if mustBuild then
val b = StringBuilder(text.length + 16)
if quoted then
b.append('"')
var i = 0
while i < text.length do
escapedChar(b, text.charAt(i))
i += 1
if quoted then
b.append('"')
b.toString
else if quoted then "\"" + text + "\""
else text

private def escapedChar(b: StringBuilder, c: Char): Unit =
def quadNibble(b: StringBuilder, x: Int, i: Int): Unit =
if i < 4 then
quadNibble(b, x >> 4, i + 1)
val n = x & 0xF
val c = if (n < 10) '0' + n else 'a' + (n - 10)
b.append(c.toChar)
val replace = (c: @switch) match
case '\b' => "\\b"
case '\t' => "\\t"
case '\n' => "\\n"
case '\f' => "\\f"
case '\r' => "\\r"
case '"' => "\\\""
case '\'' => "\\\'"
case '\\' => "\\\\"
case c =>
if c.isControl then
b.append("\\u")
quadNibble(b, c.toInt, 0)
else
b.append(c)
return
b.append(replace)

def dclsText(syms: List[Symbol], sep: String): Text = Text(syms map dclText, sep)

Expand Down
84 changes: 65 additions & 19 deletions compiler/src/scala/quoted/runtime/impl/printers/SourceCode.scala
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Original file line number Diff line number Diff line change
@@ -1,8 +1,12 @@
package scala.quoted
package runtime.impl.printers

import dotty.tools.dotc.util.Chars

import scala.annotation.switch

import java.lang.StringBuilder

/** Printer for fully elaborated representation of the source code */
object SourceCode {

Expand Down Expand Up @@ -97,7 +101,7 @@ object SourceCode {
this += lineBreak() += "}"
}

def result(): String = sb.result()
def result(): String = sb.toString

private def lineBreak(): String = "\n" + (" " * indent)
private def doubleLineBreak(): String = "\n\n" + (" " * indent)
Expand Down Expand Up @@ -438,7 +442,7 @@ object SourceCode {
case _ =>
inParens {
printTree(term)
this += (if (dotty.tools.dotc.util.Chars.isOperatorPart(sb.last)) " : " else ": ")
this += (if Chars.isOperatorPart(sb.charAt(sb.length - 1)) then " : " else ": ")
def printTypeOrAnnots(tpe: TypeRepr): Unit = tpe match {
case AnnotatedType(tp, annot) if tp == term.tpe =>
printAnnotation(annot)
Expand Down Expand Up @@ -957,8 +961,8 @@ object SourceCode {

}

inline private val qc = '\''
inline private val qSc = '"'
inline private val qc = "\'"
inline private val qSc = "\""

def printConstant(const: Constant): this.type = const match {
case UnitConstant() => this += highlightLiteral("()")
Expand All @@ -970,8 +974,8 @@ object SourceCode {
case LongConstant(v) => this += highlightLiteral(v.toString + "L")
case FloatConstant(v) => this += highlightLiteral(v.toString + "f")
case DoubleConstant(v) => this += highlightLiteral(v.toString)
case CharConstant(v) => this += highlightString(s"${qc}${escapedChar(v)}${qc}")
case StringConstant(v) => this += highlightString(s"${qSc}${escapedString(v)}${qSc}")
case CharConstant(v) => this += highlightString(escapedChar(v))
case StringConstant(v) => this += highlightString(escapedString(v))
case ClassOfConstant(v) =>
this += "classOf"
inSquare(printType(v))
Expand Down Expand Up @@ -1445,19 +1449,61 @@ object SourceCode {
private def +=(x: Char): this.type = { sb.append(x); this }
private def +=(x: String): this.type = { sb.append(x); this }

private def escapedChar(ch: Char): String = (ch: @switch) match {
case '\b' => "\\b"
case '\t' => "\\t"
case '\n' => "\\n"
case '\f' => "\\f"
case '\r' => "\\r"
case '"' => "\\\""
case '\'' => "\\\'"
case '\\' => "\\\\"
case _ => if ch.isControl then f"${"\\"}u${ch.toInt}%04x" else String.valueOf(ch).nn
}

private def escapedString(str: String): String = str flatMap escapedChar
private def escapedChar(ch: Char): String =
if requiresFormat(ch) then
val b = StringBuilder().append(qc)
escapedChar(b, ch)
b.append(qc).toString
else
qc + ch + qc

private def escapedChar(b: StringBuilder, c: Char): Unit =
def quadNibble(b: StringBuilder, x: Int, i: Int): Unit =
if i < 4 then
quadNibble(b, x >> 4, i + 1)
val n = x & 0xF
val c = if (n < 10) '0' + n else 'a' + (n - 10)
b.append(c.toChar)
val replace = (c: @switch) match
case '\b' => "\\b"
case '\t' => "\\t"
case '\n' => "\\n"
case '\f' => "\\f"
case '\r' => "\\r"
case '"' => "\\\""
case '\'' => "\\\'"
case '\\' => "\\\\"
case c =>
if c.isControl then
b.append("\\u")
quadNibble(b, c.toInt, 0)
else
b.append(c)
return
b.append(replace)

private def requiresFormat(c: Char): Boolean = (c: @switch) match
case '\b' | '\t' | '\n' | '\f' | '\r' | '"' | '\'' | '\\' => true
case c => c.isControl

private def escapedString(text: String): String =
def mustBuild: Boolean =
var i = 0
while i < text.length do
if requiresFormat(text.charAt(i)) then return true
i += 1
false
if mustBuild then
val b = StringBuilder(text.length + 16)
b.append(qSc)
var i = 0
while i < text.length do
escapedChar(b, text.charAt(i))
i += 1
b.append(qSc)
b.toString
else
qSc + text + qSc

private val names = collection.mutable.Map.empty[Symbol, String]
private val namesIndex = collection.mutable.Map.empty[String, Int]
Expand Down
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