Fossil

static int thHexdigit(char c);
static int thEndOfLine(const char *, int);

static int  thPushFrame(Th_Interp*, Th_Frame*);
static void thPopFrame(Th_Interp*);

static int thFreeVariable(Th_HashEntry*, void*);
static int thFreeCommand(Th_HashEntry*, void*);

/*
** The following are used by both the expression and language parsers.
** Given that the start of the input string (z, n) is a language
** construct of the relevant type (a command enclosed in [], an escape
** sequence etc.), these functions determine the number of bytes
** of the input consumed by the construct. For example:

/*
** Argument pEntry points to an entry in a stack frame hash table
** (Th_Frame.paVar). Decrement the reference count of the Th_Variable
** structure that the entry points to. Free the Th_Variable if its
** reference count reaches 0.
**
** Argument pContext is a pointer to the interpreter structure.
**
** Returns non-zero if the Th_Variable was actually freed.
*/
static int thFreeVariable(Th_HashEntry *pEntry, void *pContext){
  Th_Variable *pValue = (Th_Variable *)pEntry->pData;
  pValue->nRef--;
  assert( pValue->nRef>=0 );
  if( pValue->nRef==0 ){
    Th_Interp *interp = (Th_Interp *)pContext;
    Th_Free(interp, pValue->zData);
    if( pValue->pHash ){
      Th_HashIterate(interp, pValue->pHash, thFreeVariable, pContext);
      Th_HashDelete(interp, pValue->pHash);
    }
    Th_Free(interp, pValue);
    pEntry->pData = 0;
    return 1;
  }
  return 0;
}

/*
** Argument pEntry points to an entry in the command hash table
** (Th_Interp.paCmd). Delete the Th_Command structure that the
** entry points to.
**
** Argument pContext is a pointer to the interpreter structure.
**
** Always returns non-zero.
*/
static int thFreeCommand(Th_HashEntry *pEntry, void *pContext){
  Th_Command *pCommand = (Th_Command *)pEntry->pData;
  if( pCommand->xDel ){
    pCommand->xDel((Th_Interp *)pContext, pCommand->pContext);
  }
  Th_Free((Th_Interp *)pContext, pEntry->pData);
  pEntry->pData = 0;
  return 1;
}

/*
** Push a new frame onto the stack.
*/
static int thPushFrame(Th_Interp *interp, Th_Frame *pFrame){
  pFrame->paVar = Th_HashNew(interp);

** it is created. Otherwise, an error is left in the interpreter result
** and NULL returned.
**
** If the arrayok argument is false and the named variable is an array,
** an error is left in the interpreter result and NULL returned. If
** arrayok is true an array name is Ok.
*/
struct Find {
  Th_HashEntry *pValueEntry;
  Th_HashEntry *pElemEntry;
  const char *zElem;
  int nElem;
};
typedef struct Find Find;

static Th_Variable *thFindValue(
  Th_Interp *interp,
  const char *zVar,       /* Pointer to variable name */
  int nVar,               /* Number of bytes at nVar */
  int create,             /* If true, create the variable if not found */
  int arrayok,            /* If true, an array is Ok. Otherwise array==error */
  int noerror,            /* If false, set interpreter result to error */
  Find *pFind             /* If non-zero, place output here */
){
  const char *zOuter;
  int nOuter;
  const char *zInner;
  int nInner;
  int isGlobal;

  Th_HashEntry *pEntry;
  Th_Frame *pFrame = interp->pFrame;
  Th_Variable *pValue;

  thAnalyseVarname(zVar, nVar, &zOuter, &nOuter, &zInner, &nInner, &isGlobal);
  if( pFind ){
    pFind->zElem = zInner;
    pFind->nElem = nInner;
  }
  if( isGlobal ){
    while( pFrame->pCaller ) pFrame = pFrame->pCaller;
  }

  pEntry = Th_HashFind(interp, pFrame->paVar, zOuter, nOuter, create);
  assert(pEntry || create<=0);
  if( pFind ){
    pFind->pValueEntry = pEntry;
  }
  if( !pEntry ){
    goto no_such_var;
  }

  pValue = (Th_Variable *)pEntry->pData;
  if( !pValue ){
    assert(create);

    if( !pValue->pHash ){
      if( !create ){
        goto no_such_var;
      }
      pValue->pHash = Th_HashNew(interp);
    }
    pEntry = Th_HashFind(interp, pValue->pHash, zInner, nInner, create);
    assert(pEntry || create<=0);
    if( pFind ){
      pFind->pElemEntry = pEntry;
    }
    if( !pEntry ){
      goto no_such_var;
    }
    pValue = (Th_Variable *)pEntry->pData;
    if( !pValue ){
      assert(create);
      pValue = Th_Malloc(interp, sizeof(Th_Variable));

**
** If the named variable does not exist, return TH_ERROR and leave
** an error message in the interpreter result.
*/
int Th_GetVar(Th_Interp *interp, const char *zVar, int nVar){
  Th_Variable *pValue;

  pValue = thFindValue(interp, zVar, nVar, 0, 0, 0, 0);
  if( !pValue ){
    return TH_ERROR;
  }
  if( !pValue->zData ){
    Th_ErrorMessage(interp, "no such variable:", zVar, nVar);
    return TH_ERROR;
  }

  return Th_SetResult(interp, pValue->zData, pValue->nData);
}

/*
** Return true if variable (zVar, nVar) exists.
*/
int Th_ExistsVar(Th_Interp *interp, const char *zVar, int nVar){
  Th_Variable *pValue = thFindValue(interp, zVar, nVar, 0, 1, 1, 0);
  return pValue && (pValue->zData || pValue->pHash);
}

/*
** String (zVar, nVar) must contain the name of a scalar variable or
** array member. If the variable does not exist it is created. The
** variable is set to the value supplied in string (zValue, nValue).
**
** If (zVar, nVar) refers to an existing array, TH_ERROR is returned
** and an error message left in the interpreter result.
*/
int Th_SetVar(
  Th_Interp *interp,
  const char *zVar,
  int nVar,
  const char *zValue,
  int nValue
){
  Th_Variable *pValue;

  pValue = thFindValue(interp, zVar, nVar, 1, 0, 0, 0);
  if( !pValue ){
    return TH_ERROR;
  }

  if( nValue<0 ){
    nValue = th_strlen(zValue);
  }

  pFrame = getFrame(interp, iFrame);
  if( !pFrame ){
    return TH_ERROR;
  }
  pSavedFrame = interp->pFrame;
  interp->pFrame = pFrame;
  pValue = thFindValue(interp, zLink, nLink, 1, 1, 0, 0);
  interp->pFrame = pSavedFrame;

  pEntry = Th_HashFind(interp, interp->pFrame->paVar, zLocal, nLocal, 1);
  if( pEntry->pData ){
    Th_ErrorMessage(interp, "variable exists:", zLocal, nLocal);
    return TH_ERROR;
  }
  pEntry->pData = (void *)pValue;
  pValue->nRef++;

  return TH_OK;
}

/*
** Input string (zVar, nVar) must contain the name of a scalar variable,
** an array, or an array member. If the identified variable exists, it
** is deleted and TH_OK returned. Otherwise, an error message is left
** in the interpreter result and TH_ERROR is returned.
*/
int Th_UnsetVar(Th_Interp *interp, const char *zVar, int nVar){
  Find find;
  Th_Variable *pValue;
  Th_HashEntry *pEntry;
  int rc = TH_ERROR;

  memset(&find, 0, sizeof(Find));
  pValue = thFindValue(interp, zVar, nVar, 0, 1, 0, &find);
  if( !pValue ){
    return rc;
  }

  if( pValue->zData || pValue->pHash ){
    rc = TH_OK;
  }else {
    Th_ErrorMessage(interp, "no such variable:", zVar, nVar);
  }

  /*
  ** The variable may be shared by more than one frame; therefore, make sure
  ** it is actually freed prior to freeing the parent structure.  The values
  ** for the variable must be freed now so the variable appears undefined in
  ** all frames.  The hash entry in the current frame must also be deleted
  ** now; otherwise, if the current stack frame is later popped, it will try
  ** to delete a variable which has already been freed.
  */
  if( find.zElem ){
    pEntry = find.pElemEntry;
  }else{
    pEntry = find.pValueEntry;
  }
  assert( pEntry );
  assert( pValue );
  if( thFreeVariable(pEntry, (void *)interp) ){
    if( find.zElem ){
      Th_Variable *pValue2 = find.pValueEntry->pData;
      Th_HashFind(interp, pValue2->pHash, find.zElem, find.nElem, -1);
    }else{
      Th_Free(interp, pEntry->pData);
      pEntry->pData = 0;
    }
  }else{
    if( pValue->zData ){
      Th_Free(interp, pValue->zData);
      pValue->zData = 0;
    }
    if( pValue->pHash ){
      Th_HashIterate(interp, pValue->pHash, thFreeVariable, (void *)interp);
      Th_HashDelete(interp, pValue->pHash);
      pValue->pHash = 0;
    }
  }
  if( !find.zElem ){
    thFindValue(interp, zVar, nVar, -1, 1, 1, 0);
  }
  return rc;
}

/*
** Return an allocated buffer containing a copy of string (z, n). The
** caller is responsible for eventually calling Th_Free() to free
** the returned buffer.
*/

  return p;
}

/*
** Iterate through all values currently stored in the hash table. Invoke
** the callback function xCallback for each entry. The second argument
** passed to xCallback is a copy of the fourth argument passed to this
** function.  The return value from the callback function xCallback is
** ignored.
*/
void Th_HashIterate(
  Th_Interp *interp,
  Th_Hash *pHash,
  int (*xCallback)(Th_HashEntry *pEntry, void *pContext),
  void *pContext
){
  int i;
  for(i=0; i<TH_HASHSIZE; i++){
    Th_HashEntry *pEntry;
    Th_HashEntry *pNext;
    for(pEntry=pHash->a[i]; pEntry; pEntry=pNext){
      pNext = pEntry->pNext;
      xCallback(pEntry, pContext);
    }
  }
}

/*
** Helper function for Th_HashDelete().  Always returns non-zero.
*/
static int xFreeHashEntry(Th_HashEntry *pEntry, void *pContext){
  Th_Free((Th_Interp *)pContext, (void *)pEntry);
  return 1;
}

/*
** Free a hash-table previously allocated by Th_HashNew().
*/
void Th_HashDelete(Th_Interp *interp, Th_Hash *pHash){
  if( pHash ){