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

#define MAXDIM 16
#define MAXLEN 16
#define MAXENT 256

typedef struct {
   int rowdim;
   int coldim;
   int data[MAXDIM][MAXDIM];
} matrix;

typedef struct {
   char name[MAXLEN];
} varname;

typedef struct {
   varname ID;
   matrix M;
} stentry;

stentry ST[MAXENT];
int nstentry = 0;

matrix readmatrix ( char *str )
{
   matrix M;
   char *numstr, c;
   int i, j, a;

   while ((*str == ' ') || (*str == '\t')) ++str;

   if ( (*str != '[') || (strchr(str,']') == NULL) ) {
      fprintf(stderr, "*** Invalid input matrix\n");
      M.rowdim = M.coldim = 0;
      return M;
   }

   ++str;
   M.rowdim = 1; M.coldim = 0; i = j = 0;
   while (1) {
      while ((*str == ' ') || (*str == '\t')) ++str;
      numstr = str;
      if ((*str == '-') || (*str == '+')) ++str;
      while ((*str >= '0') && (*str <= '9')) ++str;
      c = *str; *str = 0; a = atoi(numstr);
      M.data[i][j] = a; ++j; if (j > M.coldim) M.coldim = j;
      *str = c;
      while ((*str == ' ') || (*str == '\t')) ++str;
      if (*str == ']') break;
      if (*str == ',') { ++str; continue; }
      if (*str == ';') { ++str; ++M.rowdim; ++i; j = 0; continue; }
      if (!((*str >= '0') && (*str <= '9'))) {
         fprintf(stderr, "*** Invalid input matrix\n"); 
         M.rowdim = M.coldim = 0;
         return M;
      }
   }
   return M;
}

varname readvarname ( char *str, int *skip )
{
   varname v;
   int i;

   *skip = 0;
   while ((*str == ' ') || (*str == '\t')) { ++str; ++(*skip); }
   if ( ((*str >= 'A') && (*str <= 'Z')) || ((*str >= 'a') && (*str <= 'z')) ) {
      v.name[0] = *str; ++str; ++(*skip); i = 1;
      while ( ((*str >= 'A') && (*str <= 'Z')) ||
              ((*str >= 'a') && (*str <= 'z')) ||
              ((*str >= '0') && (*str <= '9')) ||
              (*str == '_') ) {
         v.name[i] = *str; ++str; ++(*skip); ++i;
      }
      v.name[i] = '\0';
      return v;
   }
   fprintf(stderr, "*** Invalid variable\n");
   v.name[0] = '\0';
   return v;
}

int stref ( varname v, int CREATE )
{
   int i;

   for (i=0; i<nstentry; ++i)
      if (!strcmp(v.name,ST[i].ID.name)) return i;
   if (!CREATE) return -1;
   strcpy(ST[nstentry].ID.name,v.name);
   ++nstentry;
   return i;
}

matrix matadd ( matrix M1, matrix M2 )
{
   matrix M;
   int i, j;

   if ( (M1.rowdim != M2.rowdim) || (M1.coldim != M2.coldim) ) {
      fprintf(stderr, "*** Incompatible matrices for addition\n");
      M.rowdim = M.coldim = 0; return M;
   }
   M.rowdim = M1.rowdim; M.coldim = M1.coldim;
   for (i=0; i<M.rowdim; ++i) for (j=0; j<M.coldim; ++j) M.data[i][j] = M1.data[i][j] + M2.data[i][j];
   return M;
}

matrix matsub ( matrix M1, matrix M2 )
{
   matrix M;
   int i, j;

   if ( (M1.rowdim != M2.rowdim) || (M1.coldim != M2.coldim) ) {
      fprintf(stderr, "*** Incompatible matrices for subtraction\n");
      M.rowdim = M.coldim = 0; return M;
   }
   M.rowdim = M1.rowdim; M.coldim = M1.coldim;
   for (i=0; i<M.rowdim; ++i) for (j=0; j<M.coldim; ++j) M.data[i][j] = M1.data[i][j] - M2.data[i][j];
   return M;
}

matrix matmul ( matrix M1, matrix M2 )
{
   matrix M;
   int i, j, k;

   if (M1.coldim != M2.rowdim) {
      fprintf(stderr, "*** Incompatible matrices for multiplication\n");
      M.rowdim = M.coldim = 0; return M;
   }
   M.rowdim = M1.rowdim; M.coldim = M2.coldim;
   for (i=0; i<M.rowdim; ++i) {
      for (j=0; j<M.coldim; ++j) {
         M.data[i][j] = 0;
         for (k=0; k<M1.coldim; ++k) M.data[i][j] += M1.data[i][k] * M2.data[k][j];
      }
   }
   return M;
}

void matprn ( stentry s )
{
   int i, j;

   printf("%s\t=\t", s.ID.name);
   if ((s.M.rowdim == 0) || (s.M.coldim == 0)) { printf("EMPTY\n"); return; }
   for (i=0; i<s.M.rowdim; ++i) {
      if (i) printf("\t\t");
      for (j=0; j<s.M.coldim; ++j) printf("%8d", s.M.data[i][j]);
      printf("\n");
   }
}

int main ( int argc, char *argv[] )
{
   char line[512], *str, op;
   varname lval, rval1, rval2;
   int skip, l, r1, r2;
   FILE *fp;

   if (argc > 1) fp = (FILE *)fopen(argv[1],"r"); else fp = NULL;

   while (1) {
      printf("$ ");
      if (fp == NULL) fgets(line,512,stdin); else { fgets(line,512,fp); printf("%s", line); }
      line[strlen(line)-1] = '\0';
      str = line;
      while ((*str == ' ') || (*str == '\t')) ++str;
      if (*str == '\0') continue;
      if (!strncmp(str,"exit",4)) break;
      lval = readvarname(str, &skip); str += skip;
      if (lval.name[0] == '\0') continue;
      while ((*str == ' ') || (*str == '\t')) ++str;
      if (*str != '=') { fprintf(stderr, "*** Invalid input line\n"); continue; }
      ++str;
      while ((*str == ' ') || (*str == '\t')) ++str;
      l = stref(lval,1);
      if (*str == '[') { ST[l].M = readmatrix(str); matprn(ST[l]); continue; }
      rval1 = readvarname(str, &skip); str += skip;
      r1 = stref(rval1,0);
      if (r1 < 0) {
         fprintf(stderr, "*** Bad variable \"%s\"\n", rval1.name); matprn(ST[l]); continue;
      }
      while ((*str == ' ') || (*str == '\t')) ++str;
      op = *str; ++str;
      if (op == '\0') {
         ST[l].M = ST[r1].M;
         matprn(ST[l]);
         continue;
      }
      while ((*str == ' ') || (*str == '\t')) ++str;
      rval2 = readvarname(str, &skip); str += skip;
      if ((op != '+') && (op != '-') && (op != '*')) {
         fprintf(stderr, "*** Invalid input line\n");
         continue;
      }
      r2 = stref(rval2,0);
      if (r2 < 0) {
         fprintf(stderr, "*** Bad variable \"%s\"\n", rval2.name);
         matprn(ST[l]);
         continue;
      }
      switch (op) {
         case '+': ST[l].M = matadd(ST[r1].M,ST[r2].M); break;
         case '-': ST[l].M = matsub(ST[r1].M,ST[r2].M); break;
         case '*': ST[l].M = matmul(ST[r1].M,ST[r2].M); break;
      }
      matprn(ST[l]);
   }
   if (fp != NULL) fclose(fp);
   exit(0);
}