Attempted to simplify hresultwrap.cpp through a Scanner class, similar to Go's bufio.Scanner. There are a few snags right now...
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Pietro Gagliardi
parent
d09be0d5fc
commit
b769b37189
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@ -19,98 +19,99 @@ bool generate(std::vector<char> *genline, FILE *fout)
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return nw == genout.size();
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}
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struct process {
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// each of these returns the number of bytes in buf that were processed
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size_t (*state)(struct process *p, const char *buf, size_t n, FILE *fout);
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class Scanner {
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FILE *fin;
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char *buf;
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const char *p;
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size_t n;
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std::vector<char> *line;
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bool eof;
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bool error;
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std::vector<char> *genline;
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public:
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Scanner(FILE *fin);
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~Scanner(void);
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bool Scan(void);
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std::vector<char>::const_iterator BytesBegin(void) const;
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std::vector<char>::const_iterator BytesEnd(void) const;
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bool Error(void) const;
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};
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static size_t stateError(struct process *p, const char *buf, size_t n, FILE *fout)
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{
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p->error = true;
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return n;
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}
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size_t stateCopyLine(struct process *p, const char *buf, size_t n, FILE *fout);
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size_t stateGenerate(struct process *p, const char *buf, size_t n, FILE *fout);
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size_t stateNewLine(struct process *p, const char *buf, size_t n, FILE *fout)
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{
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if (n > 0 && buf[0] == '@') {
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p->state = stateGenerate;
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return 1; // skip the @
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}
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p->state = stateCopyLine;
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return 0; // don't skip anything
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}
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size_t stateCopyLine(struct process *p, const char *buf, size_t n, FILE *fout)
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{
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size_t nw;
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size_t j;
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for (j = 0; j < n; j++)
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if (buf[j] == '\n') {
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// include the newline; that's being copied too
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j++;
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break;
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}
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nw = fwrite(buf, sizeof (char), j, fout);
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if (nw != j) {
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p->state = stateError;
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return 0;
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}
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// and on to the next line
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p->state = stateNewLine;
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return j;
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}
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size_t stateGenerate(struct process *p, const char *buf, size_t n, FILE *fout)
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{
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size_t j;
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if (p->genline == NULL)
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p->genline = new std::vector<char>;
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for (j = 0; j < n; j++)
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if (buf[j] == '\n')
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// do NOT include the newline this time
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break;
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p->genline->insert(p->genline->end(), buf, buf + j);
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if (j == n) // '\n' not found; not finished with the line yet
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return j;
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// finished with the line; process it and continue
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if (!generate(p->genline, fout)) {
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p->state = stateError;
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return 0;
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}
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p->state = stateNewLine;
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delete p->genline;
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p->genline = NULL;
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// buf[j] == '\n' and generate() took care of printing a newline
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return j + 1;
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}
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void processInit(struct process *p)
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{
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memset(p, 0, sizeof (struct process));
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p->state = stateNewLine;
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}
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bool process(struct process *p, const char *buf, size_t n, FILE *fout)
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{
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size_t np;
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while (n != 0) {
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np = (*(p->state))(p, buf, n, fout);
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buf += np;
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n -= np;
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}
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return !p->error;
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}
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#define nbuf 1024
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Scanner::Scanner(FILE *fin)
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{
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this->fin = fin;
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this->buf = new char[nbuf];
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this->p = this->buf;
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this->n = 0;
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this->line = new std::vector<char>;
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this->eof = false;
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this->error = false;
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}
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Scanner::~Scanner(void)
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{
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delete this->line;
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delete[] this->buf;
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}
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bool Scanner::Scan(void)
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{
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if (this->eof || this->error)
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return false;
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this->line->clear();
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for (;;) {
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if (this->n > 0) {
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size_t j;
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bool haveline;
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haveline = false;
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for (j = 0; j < this->n; j++)
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if (this->p[j] == '\n') {
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haveline = true;
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break;
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}
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this->line->insert(this->line->end(), this->p, this->p + j);
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this->p += j;
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this->n -= j;
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if (haveline) {
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// swallow the \n for the next time through
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this->p++;
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this->n--;
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return true;
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}
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// otherwise, the buffer was exhausted in the middle of a line, so fall through
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}
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// need to refill the buffer
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this->n = fread(this->buf, sizeof (char), nbuf, this->fin);
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if (this->n < nbuf) {
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// TODO what if this->eof && this->error? the C standard does not expressly disallow this
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this->eof = feof(this->fin) != 0;
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this->error = ferror(this->fin) != 0;
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if (this->eof || this->error)
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return false;
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// otherwise process this last chunk of the file
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}
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this->p = this->buf;
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}
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}
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std::vector<char>::const_iterator Scanner::BytesBegin(void) const
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{
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return this->line->cbegin();
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}
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std::vector<char>::const_iterator Scanner::BytesEnd(void) const
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{
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return this->line->cend();
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}
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bool Scanner::Error(void) const
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{
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return this->error;
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}
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int main(int argc, char *argv[])
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{
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FILE *fin = NULL, *fout = NULL;
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