qmake language 的字符串替换操作的规则为:
VAR ~= s[seprator]pattern[seprator]replace[seprator]?[gqi]
1、必须以s开头
2、seprator需要自己指定,可以是任意字符
3、pattern为正则表达式的内容,可以参看正则表达式规则:正则表达式(全)
4、replace表示要替换成的目标内容,用于替换VAR中存放的字符串中满足pattern的部分
5、seprator最多有三个,pattern和replace中不能含有seprator,含有三个以上的seprator会被报错。
6、gqi是可选的,可单选或多选,顺序随意,可有可无。
(1)g表示对VAR中所有词单元都做操作,否则只对VAR中第一个词做操作。VAR词单元仅以空格为界限,比如VAR="aa bb" 表示VAR有两个词单元,VAR="aa,bb",表示VAR只有一个词单元。
(2)q表示对pattern中的特殊字符进行转义
(3)i表示正则表达式匹配规则区分大小写。
#用 '/' 做seprator
VAR = helLo world,for fun(tt)
VAR ~= s/l/t/gi #将VAR中所有词单元的l替换成t,不区分大小写
message($$VAR) #输出:Project MESSAGE: hetto wortd,for fun(tt)
VAR = helLo world,for fun(tt)
VAR ~= s/(tt)/-/gi #将括号中的字符串"tt"替换成"-"
message($$VAR) #输出:Project MESSAGE: hetto wortd,for fun(-)
VAR = helLo world,for fun(tt)(TT)
VAR ~= s/(tt)/-/qg #先对pattern进行转义,pattern变成"\(tt\)",然后将VAR中存放的字符串所有词单元中的"(tt)"用"-"进行替换,区分大小写。等价于VAR~=s/\(tt\)/-/g
message($$VAR) #输出:Project MESSAGE: hetto wortd,for fun-(TT)
#用 '\'' 做seprator
VAR = helLo world,for fun(tt)
VAR ~= s\'[()]\'-\'g #对VAR中存放的字符串的所有词单元中的'('和')'用"-"进行替换
message($$VAR) #输出:Project MESSAGE: hetto wortd,for fun-tt-
杂谈:qmake解析正则表达式的源码
//E:\workspace\QtWork\qmake\library\qmakeevaluator.cpp
QMakeEvaluator::VisitReturn QMakeEvaluator::visitProVariable(
ushort tok, const ProStringList &curr, const ushort *&tokPtr)
{
.......
if (tok == TokReplace) { // ~=
// DEFINES ~= s/a/b/?[gqi]
ProStringList varVal;
if (expandVariableReferences(tokPtr, sizeHint, &varVal, true) == ReturnError)
return ReturnError;
const QStringRef &val = varVal.at(0).toQStringRef();
if (val.length() < 4 || val.at(0) != QLatin1Char('s')) {
evalError(fL1S("The ~= operator can handle only the s/// function."));
return ReturnTrue;
}
QChar sep = val.at(1);
auto func = val.split(sep, QString::KeepEmptyParts);
if (func.count() < 3 || func.count() > 4) {
evalError(fL1S("The s/// function expects 3 or 4 arguments."));
return ReturnTrue;
}
bool global = false, quote = false, case_sense = false;
if (func.count() == 4) {
global = func[3].indexOf(QLatin1Char('g')) != -1;
case_sense = func[3].indexOf(QLatin1Char('i')) == -1;
quote = func[3].indexOf(QLatin1Char('q')) != -1;
}
QString pattern = func[1].toString();
QString replace = func[2].toString();
if (quote)
pattern = QRegExp::escape(pattern);
QRegExp regexp(pattern, case_sense ? Qt::CaseSensitive : Qt::CaseInsensitive);
// We could make a union of modified and unmodified values,
// but this will break just as much as it fixes, so leave it as is.
replaceInList(&valuesRef(varName), regexp, replace, global, m_tmp2);
debugMsg(2, "replaced %s with %s", dbgQStr(pattern), dbgQStr(replace));
}
...
}
-----------------
//D:\Qt\Qt5.12.0\5.12.0\Src\qtbase\src\corelib\tools\qregexp.cpp
QString QRegExp::escape(const QString &str)
{
QString quoted;
const int count = str.count();
quoted.reserve(count * 2);
const QLatin1Char backslash('\\');
for (int i = 0; i < count; i++) {
switch (str.at(i).toLatin1()) {
case '$':
case '(':
case ')':
case '*':
case '+':
case '.':
case '?':
case '[':
case '\\':
case ']':
case '^':
case '{':
case '|':
case '}':
quoted.append(backslash);
}
quoted.append(str.at(i));
}
return quoted;
}