付録：csv2tsvソースコードほか

tasks.json

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "Clang",
            "type": "process",
            "command": "make",
            "args": [
                "build"
            ],
            "problemMatcher": [],
            "group": {
                "kind": "build",
                "isDefault": true
            }
        },
        {
            "label": "Test",
            "type": "process",
            "command": "make",
            "args": [
                "test"
            ],
            "problemMatcher": [],
            "group": {
                "kind": "build",
                "isDefault": true
            }
        }
    ]
}

Makefile

CMD=    csv2tsv.exe

SRCS=   $(wildcard *.c)
OBJS=   $(SRCS:.c=.o)

CC= clang
CFLAGS+=-g

build: $(CMD)

$(CMD): $(OBJS)
    $(CC) $(CFLAGS) -o $(CMD) $(OBJS)

.c.o:
    $(CC) -c $< -o $@

test: $(CMD)
    pwsh .\tests\test.ps1

clean:
    rm -f *.exe
    rm -f *.o
    rm -f *.ilk
    rm -f *.pdb

main.h

int csv2tsv(const char *, int, char *, int);
char *file2str(const char *)

main.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "main.h"

int main(int argc, char *argv[]) {
  char *csvdata, *tsvdata;
  int csvdata_bytes, tsvdata_bytes;

  csvdata = file2str(argv[1]);
  csvdata_bytes = strlen(csvdata);

  tsvdata_bytes = csvdata_bytes;
  tsvdata = calloc(tsvdata_bytes + 1, sizeof(char));

  csv2tsv(csvdata, csvdata_bytes, tsvdata, tsvdata_bytes);

  printf("%s", tsvdata);

  return 0;
}

util_csv.c

#include <stdbool.h>

static bool record_outputed;

static char gettsvchar(const char);

int csv2tsv(const char *ibuf, int ibufsize, char *obuf, int obufsize) {
  // When the target is empty, no processing is done.
  if (0 == ibufsize)
    return 0;

  const char *p_i, *end_i;
  char *p_o;
  int tsv_len = 0;

  p_i = ibuf;
  end_i = &ibuf[ibufsize - 1];

  p_o = obuf;

  // Indicates the state during parsing.
  typedef enum FIELD_STATUS {
    FIELD_END,
    IN_FIELD,
    IN_QUOTED_FIELD
  } record_status;
  record_status rs = FIELD_END;

  record_outputed = false;
  while (1) {
    if ('\n' == *p_i) {
      if (!record_outputed) {
        // nothing
      }
      rs = FIELD_END;
      *p_o = gettsvchar('\n');
      ++p_o;
      ++tsv_len;
    } else {
      switch (rs) {
      case FIELD_END:
        if (',' == *p_i) {
          // nothing
        } else if ('"' == *p_i) {
          rs = IN_QUOTED_FIELD;
        } else {
          rs = IN_FIELD;
          *p_o = gettsvchar(*p_i);
          ++p_o;
          ++tsv_len;
        }
        break;
      case IN_FIELD:
        if (',' == *p_i) {
          rs = FIELD_END;
        } else {
          *p_o = gettsvchar(*p_i);
          ++p_o;
          ++tsv_len;
        }
        break;
      case IN_QUOTED_FIELD:
        if ('"' == *p_i) {
          if (p_i == end_i) {
            rs = FIELD_END;
          } else if (',' == *(p_i + 1)) {
            rs = FIELD_END;
            ++p_i;
          } else if ('"' == *(p_i + 1)) {
            *p_o = gettsvchar(*p_i);
            ++p_o;
            ++tsv_len;
            ++p_i;
          }
        } else {
          *p_o = gettsvchar(*p_i);
          ++p_o;
          ++tsv_len;
        }
        break;
      }

      switch (rs) {
      case FIELD_END:
        *p_o = '\t';
        ++p_o;
        ++tsv_len;
        record_outputed = false;
        break;
      case IN_FIELD:
      case IN_QUOTED_FIELD:
        break;
      }
    }

    if (p_i == end_i || tsv_len == obufsize)
      break;
    else
      ++p_i;
  }

  return tsv_len;
}

static char gettsvchar(const char c) {
  record_outputed = true;
  if ('\t' == c) {
    return ' ';
  } else {
    return c;
  }
}

util_file.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>

char *file2str(const char *filepath) {
  struct stat st;
  int filesize, c;

  char *buf, *p;

  FILE *fp;

  stat(filepath, &st);
  filesize = st.st_size;

  buf = calloc(filesize + 1, sizeof(char));
  p = buf;

  fp = fopen(filepath, "r");
  for (int i = 0; i < filesize; i++) {
    c = fgetc(fp);
    if (EOF == c) {
      break;
    }
    *p = (char)c;
    ++p;
  }

  return buf;
}

参考