int debuggerlines=5;

int debuggerlines=5;

int sourceline(string file, string text)
{
string file=locatefile(file);
string[] source=input(file);
for(int line=0; line < source.length; ++line)
if(find(source[line],text) >= 0) return line+1;
write("no matching line in "+file+": \""+text+"\"");
return 0;
}

void stop(string file, string text, code s=quote{})
{
int line=sourceline(file,text);
if(line > 0) stop(file,line,s);
}

void clear(string file, string text)
{
int line=sourceline(file,text);
if(line > 0) clear(file,line);
}

// Enable debugging.
bool debugging=true;

// Variables used by conditional expressions:
// e.g. stop("test",2,quote{ignore=(++count <= 10);});

bool ignore;
int count=0;

string debugger(string file, int line, int column, code s=quote{})
{
int verbose=settings.verbose;
settings.verbose=0;
_eval(s,true);
if(ignore) {
ignore=false;
settings.verbose=verbose;
return "c";
}
static string s;
if(debugging) {
static string lastfile;
static string[] source;
bool help=false;
while(true) {
if(file != lastfile && file != "-") {source=input(file); lastfile=file;}
write();
for(int i=max(line-debuggerlines,0); i < min(line,source.length); ++i)
write(source[i]);
for(int i=0; i < column-1; ++i)
write(" ",none);
write("^"+(verbose == 5 ? " trace" : ""));

if(help) {
write("c:continue f:file h:help i:inst n:next r:return s:step t:trace q:quit x:exit");
help=false;
}

string Prompt=file+": "+(string) line+"."+(string) column;
Prompt += "? [%s] ";
s=getstring(name="debug",default="h",prompt=Prompt,store=false);
if(s == "h" || s == "?") {help=true; continue;}
if(s == "c" || s == "s" || s == "n" || s == "i" || s == "f" || s == "r")
break;
if(s == "q") {debugging=false; abort();} // quit
if(s == "x") {debugging=false; return "";} // exit
if(s == "t") { // trace
if(verbose == 0) {
verbose=5;
} else {
verbose=0;
}
continue;
}
_eval(s+";",true);
}
}
settings.verbose=verbose;
return s;
}

atbreakpoint(debugger);