Param_t *parseStrings(char* str, Param_t *param)
{
//test input redirect
if(isInputRedirect(str))
{
if(param->inputRedirect != NULL)
printf("input redirect is already filled");
else
param->inputRedirect = str;
}
//test output redirect
else if(isOutputRedirect(str))
{
if(param->outputRedirect != NULL)
printf("output redirect is already filled");
else
param->outputRedirect = str;
}
//test background
else if(isBackground(str))
{
param->background = 1;
}
else
{
//add all other parameters to the argument vector
//param->argumentvector[i]
}
return param;
}
/**
* Parse Tokens
* Description: Takes a TokenList and a Command object and parses the TokenList in order
* to generate a command (list of programs in a pipeline);
* Returns: true on success; false otherwise
*/
bool parseTokens( TokenList tokens, Command * command ) {
bool success = true;
Program *currentProgram = command->program = newProgram();
bool begin = true;
for (int i = 0; i < tokens.count; i++) {
char * token = tokens.tokens[i];
// Check if we are at the beginning of a program
if ( begin ) {
if ( strncmp( token, "time", max( strlen( token ), strlen( "time" ) ) ) == 0 ) {
currentProgram->name = token;
currentProgram->next = newProgram();
currentProgram = currentProgram->next;
begin = true;
// If we have at least two tokens left and the next one is a pipe
// then make a blank timed program
// Note: This doesn't do anything since we don't allow
// piped time commands but this would help support it
// in the future and it currently prevents better
// error checking
if ( i + 2 < tokens.count && isPipe( tokens.tokens[i+1] ) ) {
currentProgram->name = NULL;
currentProgram->next = newProgram();
currentProgram = currentProgram->next;
i++;
}
// The beginning of a program cannot be <, >, &, or |
} else if ( !isRedirection( token ) && !isPipe( token ) && !isBackground( token ) ) {
currentProgram->name = token;
currentProgram->argv[currentProgram->argc++] = token;
// Don't come back here again until we process a new program
begin = false;
} else {
error("Program may not start with <, >, |, or &");
success = false;
break;
}
} else {
// Process redirection
if ( isRedirection( token ) ) {
// Only one level of redirection allowed
if ( currentProgram->redirect == DEFAULT ) {
// Need to have at least one token after a redirect
if ( i+1 < tokens.count ) {
if ( !isRedirection(tokens.tokens[i+1]) && !isPipe(tokens.tokens[i+1])
&& !isBackground(tokens.tokens[i+1]) ) {
currentProgram->redirectResource = tokens.tokens[i+1];
currentProgram->redirect = getRedirect( token );
// Skip a token
i++;
} else {
error("Expected file after a redirect");
success = false;
break;
}
}
// We can have redirections like <file or >file
else if ( strlen( token ) > 1 ) {
currentProgram->redirectResource = token+1;
currentProgram->redirect = getRedirect( token );
}
else {
error("Expected file after a redirect");
success = false;
break;
}
} else {
error("Only one level of redirection allowed");
success = false;
break;
}
// Process pipe
} else if ( isPipe( token ) ) {
// Check if there's a token after this one
if ( i+1 < tokens.count ) {
currentProgram->next = newProgram();
currentProgram = currentProgram->next;
begin = true;
}
else {
error("Expected program after pipe");
success = false;
break;
}
// Process background
} else if ( isBackground( token ) ) {
// & must be last token
if ( i+1 >= tokens.count )
command->background = true;
else {
error("& can only be placed at end of command");
success = false;
}
break;
}
// Plain old argument
else
currentProgram->argv[currentProgram->argc++] = token;
}
}
return success;
}
