From f035f7d33c7fe6460a96b2e391194c2e6a9a792d Mon Sep 17 00:00:00 2001
From: Vank143 <78201359+Vank143@users.noreply.github.com>
Date: Wed, 16 Jun 2021 17:21:32 +0200
Subject: [PATCH] Create lexer

---
 lexer | 160 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 lexer

diff --git a/lexer b/lexer
new file mode 100644
index 0000000..92dc1f2
--- /dev/null
+++ b/lexer
@@ -0,0 +1,160 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct Node Node;
+typedef struct Exploration Exploration;
+
+
+enum opcode {
+    STRING,
+    AND
+};
+struct Exploration
+{
+    int position;
+    char *text;
+};
+
+Exploration *mkExploration(char *text)
+{
+    Exploration *exploration = calloc(1,sizeof(Exploration));
+    exploration->position= 0;
+    exploration->text= text;
+    return exploration;
+}
+
+char advance(Exploration *exploration)
+{
+    return exploration->text[exploration->position++];
+}
+
+int endExploration(Exploration *exploration)
+{
+    if (exploration->position >= strlen(exploration->text))
+    {
+        return 1;
+    } else
+    {
+        return 0;
+    }
+}
+
+void setPosition(Exploration *exploration, int position)
+{
+    exploration->position= 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;
+}
+
+
+int execute(Node *node, Exploration *in)
+{
+    switch (node->type) {
+      case STRING: {
+      for (int i=0; i < strlen(node->stringValue);i++)
+      {
+          if (advance(in) != node->stringValue[i])
+          {
+              return 0;
+          }
+      }
+      if (endExploration(in)==1)
+      {
+          return 1;
+      } else
+      {
+          return -1;
+      }
+      }
+      case AND: {
+      if (execute(node->children[0], in) == 0) //si il y a eu une erreur
+      {
+          return 0;
+      } else //si ça s'est bien passé
+      {
+          return execute(node->children[1], in);
+      }
+      }
+    }
+    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=
+	      mkAnd(mkStar(mkString("a")),       // "a"*"b"*"c"*
+		    mkAnd(mkStar(mkString("b")),
+			  mkStar(mkString("c")));*/
+    if (execute(program, in)<=0)
+    {
+        printf("no match\n");
+    } else
+    {
+        printf("match\n");
+    }// 0 => no match, 1 => match
+
+
+
+
+    /*Input *in1= mkInput("hello");
+    Input *in2= mkInput("world");
+    Input *in3= mkInput("hello world");
+
+    Node *program=
+	      mkOr(mkString("hello"),       // "hello" | "world"
+		   mkString("world"));
+
+    printf("%i\n", execute(program, in));  // 0 => no match, 1 => match*/
+
+
+
+    return 0;
+}