PROGRAMA, SKIRTA APTIKTI ŽETONUS C KODE

Kaip žinoma, kad Leksinė analizė yra pirmasis kompiliatoriaus, taip pat žinomo kaip skaitytuvas, etapas. Jis paverčia įvesties programą į žetonų seką.
C programa susideda iš įvairių žetonų, o tokenas yra raktinis žodis, identifikatorius, konstanta, eilutės raidė arba simbolis.
Pavyzdžiui:

naudojantis internetu

Raktažodžiai: trumpam, jei ir pan.
Identifikatorius: kintamojo pavadinimo funkcijos pavadinimas ir kt.
Operatoriai: „+“ „++“ „-“ ir kt.
skyrikliai: ' ';' ir tt

Pavyzdys: įvedimui'int a = b + 1c;'tai atpažins'int'kaip raktinį žodį'a'kaip identifikatorius'='kaip operatorius ir pan.

Prieiga:

Idea yra suskaidyti įvesties eilutę (C kodą) į žetonus, tokius kaip raktiniai žodžiai identifikatoriai operatoriai sveikieji skaičiai ir realieji skaičiai.
Jis tikrina kiekvieną žetoną naudodamas pagalbinių funkcijų (isKeyword isInteger validIdentifierir tt) ir išspausdina jos kategoriją.

Žemiau yra programa, skirta spausdinti visus raktinius žodžius literalai galiojantys identifikatoriai negaliojantys identifikatoriai sveikasis skaičius realusis skaičius nurodytame C kode:

C++

#include  #include  #include  #include  // Returns 'true' if the character is a DELIMITER. bool isDelimiter(char ch) {  if (ch == ' ' || ch == '+' || ch == '-' || ch == '*' ||   ch == '/' || ch == '' || ch == ';' || ch == '>' ||   ch == '<' || ch == '=' || ch == '(' || ch == ')' ||   ch == '[' || ch == ']' || ch == '{' || ch == '}')  return (true);  return (false); } // Returns 'true' if the character is an OPERATOR. bool isOperator(char ch) {  if (ch == '+' || ch == '-' || ch == '*' ||   ch == '/' || ch == '>' || ch == '<' ||   ch == '=')  return (true);  return (false); } // Returns 'true' if the string is a VALID IDENTIFIER. bool validIdentifier(char* str) {  if (str[0] == '0' || str[0] == '1' || str[0] == '2' ||  str[0] == '3' || str[0] == '4' || str[0] == '5' ||   str[0] == '6' || str[0] == '7' || str[0] == '8' ||   str[0] == '9' || isDelimiter(str[0]) == true)  return (false);  return (true); } // Returns 'true' if the string is a KEYWORD. bool isKeyword(char* str) {  if (!strcmp(str 'if') || !strcmp(str 'else') ||  !strcmp(str 'while') || !strcmp(str 'do') ||   !strcmp(str 'break') ||   !strcmp(str 'continue') || !strcmp(str 'int')  || !strcmp(str 'double') || !strcmp(str 'float')  || !strcmp(str 'return') || !strcmp(str 'char')  || !strcmp(str 'case') || !strcmp(str 'char')  || !strcmp(str 'sizeof') || !strcmp(str 'long')  || !strcmp(str 'short') || !strcmp(str 'typedef')  || !strcmp(str 'switch') || !strcmp(str 'unsigned')  || !strcmp(str 'void') || !strcmp(str 'static')  || !strcmp(str 'struct') || !strcmp(str 'goto'))  return (true);  return (false); } // Returns 'true' if the string is an INTEGER. bool isInteger(char* str) {  int i len = strlen(str);  if (len == 0)  return (false);  for (i = 0; i < len; i++) {  if (str[i] != '0' && str[i] != '1' && str[i] != '2'  && str[i] != '3' && str[i] != '4' && str[i] != '5'  && str[i] != '6' && str[i] != '7' && str[i] != '8'  && str[i] != '9' || (str[i] == '-' && i > 0))  return (false);  }  return (true); } // Returns 'true' if the string is a REAL NUMBER. bool isRealNumber(char* str) {  int i len = strlen(str);  bool hasDecimal = false;  if (len == 0)  return (false);  for (i = 0; i < len; i++) {  if (str[i] != '0' && str[i] != '1' && str[i] != '2'  && str[i] != '3' && str[i] != '4' && str[i] != '5'  && str[i] != '6' && str[i] != '7' && str[i] != '8'  && str[i] != '9' && str[i] != '.' ||   (str[i] == '-' && i > 0))  return (false);  if (str[i] == '.')  hasDecimal = true;  }  return (hasDecimal); } // Extracts the SUBSTRING. char* subString(char* str int left int right) {  int i;  char* subStr = (char*)malloc(  sizeof(char) * (right - left + 2));  for (i = left; i <= right; i++)  subStr[i - left] = str[i];  subStr[right - left + 1] = '';  return (subStr); } // Parsing the input STRING. void parse(char* str) {  int left = 0 right = 0;  int len = strlen(str);  while (right <= len && left <= right) {  if (isDelimiter(str[right]) == false)  right++;  if (isDelimiter(str[right]) == true && left == right) {  if (isOperator(str[right]) == true)  printf(''%c' IS AN OPERATORn' str[right]);  right++;  left = right;  } else if (isDelimiter(str[right]) == true && left != right  || (right == len && left != right)) {  char* subStr = subString(str left right - 1);  if (isKeyword(subStr) == true)  printf(''%s' IS A KEYWORDn' subStr);  else if (isInteger(subStr) == true)  printf(''%s' IS AN INTEGERn' subStr);  else if (isRealNumber(subStr) == true)  printf(''%s' IS A REAL NUMBERn' subStr);  else if (validIdentifier(subStr) == true  && isDelimiter(str[right - 1]) == false)  printf(''%s' IS A VALID IDENTIFIERn' subStr);  else if (validIdentifier(subStr) == false  && isDelimiter(str[right - 1]) == false)  printf(''%s' IS NOT A VALID IDENTIFIERn' subStr);  left = right;  }  }  return; } // DRIVER FUNCTION int main() {  // maximum length of string is 100 here   char str[100] = 'int a = b + 1c; ';  parse(str); // calling the parse function  return (0); }

#include  #include  #include  #include  // Returns 'true' if the character is a DELIMITER. bool isDelimiter(char ch) {  if (ch == ' ' || ch == '+' || ch == '-' || ch == '*' ||   ch == '/' || ch == '' || ch == ';' || ch == '>' ||   ch == '<' || ch == '=' || ch == '(' || ch == ')' ||   ch == '[' || ch == ']' || ch == '{' || ch == '}')  return (true);  return (false); } // Returns 'true' if the character is an OPERATOR. bool isOperator(char ch) {  if (ch == '+' || ch == '-' || ch == '*' ||   ch == '/' || ch == '>' || ch == '<' ||   ch == '=')  return (true);  return (false); } // Returns 'true' if the string is a VALID IDENTIFIER. bool validIdentifier(char* str) {  if (str[0] == '0' || str[0] == '1' || str[0] == '2' ||  str[0] == '3' || str[0] == '4' || str[0] == '5' ||   str[0] == '6' || str[0] == '7' || str[0] == '8' ||   str[0] == '9' || isDelimiter(str[0]) == true)  return (false);  return (true); } // Returns 'true' if the string is a KEYWORD. bool isKeyword(char* str) {  if (!strcmp(str 'if') || !strcmp(str 'else') ||  !strcmp(str 'while') || !strcmp(str 'do') ||   !strcmp(str 'break') ||   !strcmp(str 'continue') || !strcmp(str 'int')  || !strcmp(str 'double') || !strcmp(str 'float')  || !strcmp(str 'return') || !strcmp(str 'char')  || !strcmp(str 'case') || !strcmp(str 'char')  || !strcmp(str 'sizeof') || !strcmp(str 'long')  || !strcmp(str 'short') || !strcmp(str 'typedef')  || !strcmp(str 'switch') || !strcmp(str 'unsigned')  || !strcmp(str 'void') || !strcmp(str 'static')  || !strcmp(str 'struct') || !strcmp(str 'goto'))  return (true);  return (false); } // Returns 'true' if the string is an INTEGER. bool isInteger(char* str) {  int i len = strlen(str);  if (len == 0)  return (false);  for (i = 0; i < len; i++) {  if (str[i] != '0' && str[i] != '1' && str[i] != '2'  && str[i] != '3' && str[i] != '4' && str[i] != '5'  && str[i] != '6' && str[i] != '7' && str[i] != '8'  && str[i] != '9' || (str[i] == '-' && i > 0))  return (false);  }  return (true); } // Returns 'true' if the string is a REAL NUMBER. bool isRealNumber(char* str) {  int i len = strlen(str);  bool hasDecimal = false;  if (len == 0)  return (false);  for (i = 0; i < len; i++) {  if (str[i] != '0' && str[i] != '1' && str[i] != '2'  && str[i] != '3' && str[i] != '4' && str[i] != '5'  && str[i] != '6' && str[i] != '7' && str[i] != '8'  && str[i] != '9' && str[i] != '.' ||   (str[i] == '-' && i > 0))  return (false);  if (str[i] == '.')  hasDecimal = true;  }  return (hasDecimal); } // Extracts the SUBSTRING. char* subString(char* str int left int right) {  int i;  char* subStr = (char*)malloc(  sizeof(char) * (right - left + 2));  for (i = left; i <= right; i++)  subStr[i - left] = str[i];  subStr[right - left + 1] = '';  return (subStr); } // Parsing the input STRING. void parse(char* str) {  int left = 0 right = 0;  int len = strlen(str);  while (right <= len && left <= right) {  if (isDelimiter(str[right]) == false)  right++;  if (isDelimiter(str[right]) == true && left == right) {  if (isOperator(str[right]) == true)  printf(''%c' IS AN OPERATORn' str[right]);  right++;  left = right;  } else if (isDelimiter(str[right]) == true && left != right  || (right == len && left != right)) {  char* subStr = subString(str left right - 1);  if (isKeyword(subStr) == true)  printf(''%s' IS A KEYWORDn' subStr);  else if (isInteger(subStr) == true)  printf(''%s' IS AN INTEGERn' subStr);  else if (isRealNumber(subStr) == true)  printf(''%s' IS A REAL NUMBERn' subStr);  else if (validIdentifier(subStr) == true  && isDelimiter(str[right - 1]) == false)  printf(''%s' IS A VALID IDENTIFIERn' subStr);  else if (validIdentifier(subStr) == false  && isDelimiter(str[right - 1]) == false)  printf(''%s' IS NOT A VALID IDENTIFIERn' subStr);  left = right;  }  }  return; } // DRIVER FUNCTION int main() {  // maximum length of string is 100 here   char str[100] = 'int a = b + 1c; ';  parse(str); // calling the parse function  return (0); }

Java

import java.util.Arrays; public class Parser {  public static boolean isDelimiter(char ch) {  return ' +-*/ ;><=()[]{}'.indexOf(ch) != -1;  }  public static boolean isOperator(char ch) {  return '+-*/><='.indexOf(ch) != -1;  }  public static boolean validIdentifier(String str) {  if (str.isEmpty() || Character.isDigit(str.charAt(0)) || isDelimiter(str.charAt(0)))  return false;  return true;  }  public static boolean isKeyword(String str) {  String[] keywords = { 'if' 'else' 'while' 'do' 'break' 'continue' 'int' 'double' 'float' 'return' 'char' 'case' 'sizeof' 'long' 'short' 'typedef' 'switch' 'unsigned' 'void' 'static' 'struct' 'goto' };  return Arrays.asList(keywords).contains(str);  }  public static boolean isInteger(String str) {  if (str.isEmpty())  return false;  for (int i = 0; i < str.length(); i++) {  if (!Character.isDigit(str.charAt(i)) && !(str.charAt(i) == '-' && i == 0))  return false;  }  return true;  }  public static boolean isRealNumber(String str) {  if (str.isEmpty())  return false;  boolean hasDecimal = false;  for (int i = 0; i < str.length(); i++) {  if (!Character.isDigit(str.charAt(i)) && str.charAt(i) != '.' && !(str.charAt(i) == '-' && i == 0))  return false;  if (str.charAt(i) == '.')  hasDecimal = true;  }  return hasDecimal;  }  public static String subString(String str int left int right) {  return str.substring(left right + 1);  }  public static void parse(String str) {  int left = 0 right = 0;  int len = str.length();  while (right <= len && left <= right) {  if (!isDelimiter(str.charAt(right)))  right++;  if (isDelimiter(str.charAt(right)) && left == right) {  if (isOperator(str.charAt(right)))  System.out.println(''' + str.charAt(right) + '' IS AN OPERATOR');  right++;  left = right;  } else if (isDelimiter(str.charAt(right)) && left != right || (right == len && left != right)) {  String subStr = subString(str left right - 1);  if (isKeyword(subStr))  System.out.println(''' + subStr + '' IS A KEYWORD');  else if (isInteger(subStr))  System.out.println(''' + subStr + '' IS AN INTEGER');  else if (isRealNumber(subStr))  System.out.println(''' + subStr + '' IS A REAL NUMBER');  else if (validIdentifier(subStr) && !isDelimiter(str.charAt(right - 1)))  System.out.println(''' + subStr + '' IS A VALID IDENTIFIER');  else if (!validIdentifier(subStr) && !isDelimiter(str.charAt(right - 1)))  System.out.println(''' + subStr + '' IS NOT A VALID IDENTIFIER');  left = right;  }  }  }  public static void main(String[] args) {  String str = 'int a = b + 1c; ';  parse(str);  } }

Python

def is_delimiter(ch): return ch in ' +-*/ ;><=()[]{}' def is_operator(ch): return ch in '+-*/><=' def valid_identifier(str): if not str or str[0].isdigit() or is_delimiter(str[0]): return False return True def is_keyword(str): keywords = ['if' 'else' 'while' 'do' 'break' 'continue' 'int' 'double' 'float' 'return' 'char' 'case' 'sizeof' 'long' 'short' 'typedef' 'switch' 'unsigned' 'void' 'static' 'struct' 'goto'] return str in keywords def is_integer(str): if not str: return False for i in range(len(str)): if not str[i].isdigit() and not (str[i] == '-' and i == 0): return False return True def is_real_number(str): if not str: return False has_decimal = False for i in range(len(str)): if not str[i].isdigit() and str[i] != '.' and not (str[i] == '-' and i == 0): return False if str[i] == '.': has_decimal = True return has_decimal def sub_string(str left right): return str[left:right + 1] def parse(str): left = 0 right = 0 len_str = len(str) while right <= len_str and left <= right: if not is_delimiter(str[right]): right += 1 if is_delimiter(str[right]) and left == right: if is_operator(str[right]): print(f''{str[right]}' IS AN OPERATOR') right += 1 left = right elif is_delimiter(str[right]) and left != right or (right == len_str and left != right): sub_str = sub_string(str left right - 1) if is_keyword(sub_str): print(f''{sub_str}' IS A KEYWORD') elif is_integer(sub_str): print(f''{sub_str}' IS AN INTEGER') elif is_real_number(sub_str): print(f''{sub_str}' IS A REAL NUMBER') elif valid_identifier(sub_str) and not is_delimiter(str[right - 1]): print(f''{sub_str}' IS A VALID IDENTIFIER') elif not valid_identifier(sub_str) and not is_delimiter(str[right - 1]): print(f''{sub_str}' IS NOT A VALID IDENTIFIER') left = right if __name__ == '__main__': str = 'int a = b + 1c; ' parse(str)

Išvestis:

mylintis kriketas

'int' IS A KEYWORD 'a' IS A VALID IDENTIFIER '=' IS AN OPERATOR 'b' IS A VALID IDENTIFIER '+' IS AN OPERATOR '1c' IS NOT A VALID IDENTIFIER

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Programa, skirta aptikti žetonus C kode

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