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var cur = this.current;
if( cur >= 'A' && cur <= 'Z' || cur >= 'a' && cur <= 'z') {
  // do something
}

int p;
int l;
int c;
ch = -1;
this.capture.Clear();
if ((this.current == -2)) {
    this.Advance();
}
p = this.position;
l = this.line;
c = this.column;
// q0:
// [\t-\n\r ]
if (((((this.current >= 9) 
            && (this.current <= 10)) 
            || (this.current == 13)) 
            || (this.current == 32))) {
    this.Advance();
    goto q1;
}
// [A-Z_hj-kmqxz]
if ((((((((((this.current >= 65) 
            && (this.current <= 90)) 
            || (this.current == 95)) 
            || (this.current == 104)) 
            || ((this.current >= 106) 
            && (this.current <= 107))) 
            || (this.current == 109)) 
            || (this.current == 113)) 
            || (this.current == 120)) 
            || (this.current == 122))) {
    this.Advance();
    goto q2;
}
// [a]
if ((this.current == 97)) {
    this.Advance();
    goto q3;
}
// [b]
if ((this.current == 98)) {
    this.Advance();
    goto q22;
}
// ...snip...
q1:
// [\t-\n\r ]
if (((((this.current >= 9) 
            && (this.current <= 10)) 
            || (this.current == 13)) 
            || (this.current == 32))) {
    this.Advance();
    goto q1;
}
return FAMatch.Create(2, this.capture.ToString(), p, l, c);
q2:
// [0-9A-Z_a-z]
if ((((((this.current >= 48) 
            && (this.current <= 57)) 
            || ((this.current >= 65) 
            && (this.current <= 90))) 
            || (this.current == 95)) 
            || ((this.current >= 97) 
            && (this.current <= 122)))) {
    this.Advance();
    goto q2;
}
return FAMatch.Create(0, this.capture.ToString(), p, l, c);

Quote:

Running the code through a debugger and dropping to assembly. The only way I can do that reliably is with debug info, which may change how the JITter drops native instructions. I can't rely on it.

[System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]