Dynamic PEG for interpreted languages.
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct Node Node;
typedef struct Exploration Exploration;
enum opcode {
STRING,
AND,
OR,
STAR,
PLUS,
CLASS,
QUESTION_MARK,
EXCLAMATION_MARK,
DOT
};
struct Exploration
{
int position;
char *text;
};
Exploration *mkExploration(char *text)
{
Exploration *exploration = calloc(1,sizeof(Exploration*)); //sizeof du type pointeur
exploration->position= 0;
exploration->text= text;
return exploration;
}
void advance(Exploration *exploration, int add)
{
exploration->position+= add;
}
int atEnd(Exploration *exploration) {
return exploration->text[exploration->position] == 0;
}
void setPosition(Exploration *exploration, int position)
{
exploration->position= position;
}
int getPosition(Exploration *exploration) {
return exploration->position;
}
int currentChar(Exploration *exploration)
{
return exploration->text[exploration->position];
}
char *currentText(Exploration *exploration)
{
return exploration->text + exploration->position;
}
struct Node
{
enum opcode type;
union {
char *stringValue;
Node *children[2];
};
};
Node *mkNode(enum opcode type)
{
Node *node= calloc(1, sizeof(Node));
node->type= type;
return node;
}
Node *mkString(char *value)
{
Node *node= mkNode(STRING);
node->stringValue= value;
return node;
}
Node *mkAnd(Node *node1, Node *node2)
{
Node *node= mkNode(AND);
node->children[0]= node1;
node->children[1]= node2;
return node;
}
Node *mkStar(Node *child)
{
Node *node= mkNode(STAR);
node->children[0]= child;
return node;
}
Node *mkPlus(Node *child)
{
Node *node= mkNode(PLUS);
node->children[0]= child;
return node;
}
Node *mkOr(Node *node1, Node *node2)
{
Node *node= mkNode(OR);
node->children[0]= node1;
node->children[1]= node2;
return node;
}
Node *mkClass(char* str)
{
Node *node= mkNode(CLASS);
node->stringValue= str;
return node;
}
Node *mkQuestionMark(Node *child)
{
Node *node= mkNode(QUESTION_MARK);
node->children[0]= child;
return node;
}
Node *mkExclamationMark(Node *child)
{
Node *node= mkNode(EXCLAMATION_MARK);
node->children[0]= child;
return node;
}
Node *mkDot()
{
Node *node= mkNode(DOT);
return node;
}
int execute(Node *node, Exploration *in)
{
switch (node->type) {
case STRING: {
int length= strlen(node->stringValue);
if (strncmp(currentText(in), node->stringValue, length)) {
return 0;
}
advance(in, length);
return 1;
}
case AND: {
int pos= getPosition(in);
if (!execute(node->children[0], in)) //si il y a eu une erreur
{
return 0;
} //si ça s'est bien passé
if (!execute(node->children[1], in)) {
setPosition(in, pos);
return 0;
}
return 1;
}
case OR: {
if (execute(node->children[0], in)) {
return 1;
}
return execute(node->children[1], in);
}
case STAR: {
while (execute(node->children[0], in));
return 1;
}
case PLUS: {
if (!execute(node->children[0], in)) {
return 0;
}
while (execute(node->children[0], in));
return 1;
}
case CLASS: {
if (!currentChar(in)) {
return 0;
}
if (strchr(node->stringValue, currentChar(in))) {
advance(in, 1);
return 1;
}
return 0;
}
case QUESTION_MARK: {
execute(node->children[0], in);
return 1;
}
case EXCLAMATION_MARK: {
int pos= getPosition(in);
if (!execute(node->children[0], in)) {
return 1;
}
setPosition(in, pos);
return 0;
}
case DOT: {
if (atEnd(in)) {
return 0;
}
advance(in, 1);
return 1;
}
}
printf("this cannot happen\n");
abort();
}
int main(int argc, char **argv)
{
Exploration *in= mkExploration("aabbcc");
/*Node *program=
mkString("aabbcc");
Node *program=
mkAnd(mkString("aab"),
mkString("bcc"));*/
/*Node *program=
mkAnd(mkString("aa"),
mkAnd(mkString("bb"),
mkString("cc")));*/
/*Node *program=
mkOr(mkPlus(mkString("a")), // "a"*"b"*"c"*
mkAnd(mkStar(mkString("b")),
mkStar(mkString("c"))));*/
Node *program= mkStar(mkClass("abc"));
if (!execute(program, in) || !atEnd(in))
{
printf("no match, current position : %i\n", getPosition(in));
} else
{
printf("match, current position : %i\n", getPosition(in));
}// 0 => no match, 1 => match
return 0;
}