// -*- mode: java;  -*-

// Ary/Vector of u8s - a resizable array of bytes.
struct aryu8 {
    u32 !len = 0;
    u8[] !buf;

    new aryu8 = { -> buf = new u8[1]; };

    // Grow as needed
    val _grow = { int len2 ->
        if( len+len2 < buf# ) return self;
        int newlen = buf# * 2;
        while( len+len2 >= newlen ) newlen *= 2;
        u8[] !buf2 = new u8[newlen];
        ary.copy(buf2,0,buf,0,buf#);
        buf = buf2;
        self;
    };

    val clear = { -> len = 0; self; };

    // Add a character to aryu8
    val add = { u8 c ->
        _grow(1).buf[len++] = c;
        self;
    };

    // Add all of a plain array to the aryu8
    val addAry = { u8[~] xs ->
        _grow(xs#);
        ary.copy(buf,len,xs,0,xs#);
        len += xs#;
        self;
    };

    // Remove x bytes from the tail.
    val undo = { int x ->
        len = len >= x ? len-x : 0;
        self;
    };

    // Print ASCII number into aryu8
    val num = { i64 x ->
        if( !x ) { add('0'); return self; }
        if( x < 0 ) { add('-'); x = -x; }
        i64 ten = 1, log = 0;
        while( ten <= x ) { ten *= 10; log++; }
        for( int i=0; i<log; i++ ) {
            ten /= 10;
            i64 q = x/ten;
            u8 digit = q+'0';
            add(digit);
            x -= q*ten;
        }
        self;
    };

    // Write to fd, returns the number of bytes written (len).
    val write = { i32 fd ->
        i64 ptr = buf; // Cast buffer pointer to i64 for native C call
        libc.write(fd,ptr,len);
    };
};


// Parse one integer, ignore trailing data; returns 0 with an empty string.
// If you want a more robust parsing, use the `scan` class
val atoi = { u8[~] str ->
    int x = 0;
    while( x < str# && str[x] <= ' ' ) x++;
    if( x == str# ) return 0;
    bool neg = false;
    if( str[x]=='-' ) { neg=true; x++; }
    i64 n = 0;
    while( x < str# && '0' <= str[x] <= '9' )
        n = n*10 + str[x++]-'0';
    return neg ? -n : n;
};

// Zero-terminate string for libc strings.  No error checking, just copies and
// appends a zero.
{ u8[~] -> u8[] } str0 = { u8[~] str ->
  u8[] !strz = new u8[str#+1];
  ary.copy(strz,0,str,0,str#);
  strz[str#] = '\0';
  strz;
};