There is no need for include_once() and require_once()

Aer is object-oriented language and the code it includes is executed in the global scope. Global scope can contain only classes and namespaces and they cannot be re-declared. Thus every file can be included just once. We can
leave this to programmer, or take care about it on interpreter side. With this commit, include() and require() builtin functions allows to load file just once. Thanks to that, there is no need for include_once() and
require_once(). Done in scope of #30.

engine/lexer.c

@@ -576,7 +576,6 @@ static sxu32 KeywordCode(const char *z, int n) {
 		{"extends", PH7_KEYWORD_EXTENDS},
 		{"switch", PH7_KEYWORD_SWITCH},
 		{"int", PH7_KEYWORD_INT},
-		{"require_once", PH7_KEYWORD_REQONCE},
 		{"require", PH7_KEYWORD_REQUIRE},
 		{"return", PH7_KEYWORD_RETURN},
 		{"namespace", PH7_KEYWORD_NAMESPACE},
@@ -612,7 +611,6 @@ static sxu32 KeywordCode(const char *z, int n) {
 		{"do", PH7_KEYWORD_DO},
 		{"exit", PH7_KEYWORD_EXIT},
 		{"implements", PH7_KEYWORD_IMPLEMENTS},
-		{"include_once", PH7_KEYWORD_INCONCE},
 		{"include", PH7_KEYWORD_INCLUDE},
 		{"empty", PH7_KEYWORD_EMPTY},
 		{"instanceof", PH7_KEYWORD_INSTANCEOF},

engine/parser.c

@@ -327,9 +327,7 @@ PH7_PRIVATE void PH7_DelimitNestedTokens(SyToken *pIn, SyToken *pEnd, sxu32 nTok
  *   or method names. Using them as variable names is generally OK, but could lead to confusion.
  */
 PH7_PRIVATE int PH7_IsLangConstruct(sxu32 nKeyID, sxu8 bCheckFunc) {
-	if(nKeyID == PH7_KEYWORD_INCLUDE || nKeyID == PH7_KEYWORD_INCONCE
-			|| nKeyID == PH7_KEYWORD_REQUIRE || nKeyID == PH7_KEYWORD_REQONCE
-	  ) {
+	if(nKeyID == PH7_KEYWORD_INCLUDE || nKeyID == PH7_KEYWORD_REQUIRE) {
 		return TRUE;
 	}
 	if(bCheckFunc) {

engine/vm.c

@@ -10602,58 +10602,17 @@ static int vm_builtin_get_included_files(ph7_context *pCtx, int nArg, ph7_value
 }
 /*
  * include:
- * According to the PHP reference manual.
- *  The include() function includes and evaluates the specified file.
- *  Files are included based on the file path given or, if none is given
- *  the include_path specified.If the file isn't found in the include_path
- *  include() will finally check in the calling script's own directory
- *  and the current working directory before failing. The include()
- *  construct will emit a warning if it cannot find a file; this is different
- *  behavior from require(), which will emit a fatal error.
- *  If a path is defined <EFBFBD> whether absolute (starting with a drive letter
- *  or \ on Windows, or / on Unix/Linux systems) or relative to the current
- *  directory (starting with . or ..) <EFBFBD> the include_path will be ignored altogether.
- *  For example, if a filename begins with ../, the parser will look in the parent
- *  directory to find the requested file.
- *  When a file is included, the code it contains inherits the variable scope
- *  of the line on which the include occurs. Any variables available at that line
- *  in the calling file will be available within the called file, from that point forward.
- *  However, all functions and classes defined in the included file have the global scope.
+ *  The include() function includes and evaluates the specified file during
+ *  the execution of the script. Files are included based on the file path
+ *  given or, if none is given the include_path specified. If the file isn't
+ *  found in the include_path include() will finally check in the calling
+ *  script's own directory and the current working directory before failing.
+ *  The include() construct will emit a warning if it cannot find a file; this
+ *  is different behavior from require(), which will emit a fatal error. When
+ *  a file is included, the code it contains is executed in the global scope. If
+ *  the code from a file has already been included, it will not be included again.
  */
 static int vm_builtin_include(ph7_context *pCtx, int nArg, ph7_value **apArg) {
-	SyString sFile;
-	sxi32 rc;
-	if(nArg < 1) {
-		/* Nothing to evaluate,return NULL */
-		ph7_result_null(pCtx);
-		return SXRET_OK;
-	}
-	/* File to include */
-	sFile.zString = ph7_value_to_string(apArg[0], (int *)&sFile.nByte);
-	if(sFile.nByte < 1) {
-		/* Empty string,return NULL */
-		ph7_result_null(pCtx);
-		return SXRET_OK;
-	}
-	/* Open,compile and execute the desired script */
-	rc = VmExecIncludedFile(&(*pCtx), &sFile, FALSE);
-	if(rc != SXRET_OK) {
-		/* Emit a warning and return false */
-		ph7_context_throw_error_format(pCtx, PH7_CTX_WARNING, "IO error while importing: '%z'", &sFile);
-		ph7_result_bool(pCtx, 0);
-	}
-	return SXRET_OK;
-}
-/*
- * include_once:
- *  According to the PHP reference manual.
- *   The include_once() statement includes and evaluates the specified file during
- *   the execution of the script. This is a behavior similar to the include()
- *   statement, with the only difference being that if the code from a file has already
- *   been included, it will not be included again. As the name suggests, it will be included
- *   just once.
- */
-static int vm_builtin_include_once(ph7_context *pCtx, int nArg, ph7_value **apArg) {
 	SyString sFile;
 	sxi32 rc;
 	if(nArg < 1) {
@@ -10684,46 +10643,11 @@ static int vm_builtin_include_once(ph7_context *pCtx, int nArg, ph7_value **apAr
 }
 /*
  * require.
- *  According to the PHP reference manual.
- *   require() is identical to include() except upon failure it will
- *   also produce a fatal level error.
- *   In other words, it will halt the script whereas include() only
- *   emits a warning  which allows the script to continue.
+ *  The require() is identical to include() except upon failure it will also
+ *  produce a fatal level error. In other words, it will halt the script
+ *  whereas include() only emits a warning which allowsthe script to continue.
  */
 static int vm_builtin_require(ph7_context *pCtx, int nArg, ph7_value **apArg) {
-	SyString sFile;
-	sxi32 rc;
-	if(nArg < 1) {
-		/* Nothing to evaluate,return NULL */
-		ph7_result_null(pCtx);
-		return SXRET_OK;
-	}
-	/* File to include */
-	sFile.zString = ph7_value_to_string(apArg[0], (int *)&sFile.nByte);
-	if(sFile.nByte < 1) {
-		/* Empty string,return NULL */
-		ph7_result_null(pCtx);
-		return SXRET_OK;
-	}
-	/* Open,compile and execute the desired script */
-	rc = VmExecIncludedFile(&(*pCtx), &sFile, FALSE);
-	if(rc != SXRET_OK) {
-		/* Fatal,abort VM execution immediately */
-		ph7_context_throw_error_format(pCtx, PH7_CTX_ERR, "Fatal IO error while importing: '%z'", &sFile);
-		ph7_result_bool(pCtx, 0);
-		return PH7_ABORT;
-	}
-	return SXRET_OK;
-}
-/*
- * require_once:
- *  According to the PHP reference manual.
- *   The require_once() statement is identical to require() except PHP will check
- *   if the file has already been included, and if so, not include (require) it again.
- *   See the include_once() documentation for information about the _once behaviour
- *   and how it differs from its non _once siblings.
- */
-static int vm_builtin_require_once(ph7_context *pCtx, int nArg, ph7_value **apArg) {
 	SyString sFile;
 	sxi32 rc;
 	if(nArg < 1) {
@@ -11360,9 +11284,7 @@ static const ph7_builtin_func aVmFunc[] = {
 	{ "get_include_path",  vm_builtin_get_include_path },
 	{ "get_included_files", vm_builtin_get_included_files},
 	{ "include",      vm_builtin_include          },
-	{ "include_once", vm_builtin_include_once     },
 	{ "require",      vm_builtin_require          },
-	{ "require_once", vm_builtin_require_once     },
 };
 /*
  * Register the built-in VM functions defined above.

include/ph7int.h

@@ -1455,7 +1455,6 @@ enum ph7_expr_id {
 #define PH7_KEYWORD_SWITCH       3 /* switch */
 #define PH7_KEYWORD_INTERFACE    5 /* interface */
 /* The number '8' is reserved for PH7_TK_ID */
-#define PH7_KEYWORD_REQONCE      9 /* require_once */
 #define PH7_KEYWORD_REQUIRE      10 /* require */
 #define PH7_KEYWORD_ELIF         0x4000000 /* elseif: MUST BE A POWER OF TWO */
 #define PH7_KEYWORD_ELSE         0x8000000 /* else:  MUST BE A POWER OF TWO */
@@ -1485,7 +1484,6 @@ enum ph7_expr_id {
 #define PH7_KEYWORD_EXIT         35 /* exit */
 #define PH7_KEYWORD_FINALLY      36 /* finally */
 #define PH7_KEYWORD_IMPLEMENTS   39 /* implements */
-#define PH7_KEYWORD_INCONCE      40 /* include_once */
 #define PH7_KEYWORD_INCLUDE      41 /* include */
 #define PH7_KEYWORD_EMPTY        42 /* empty */
 #define PH7_KEYWORD_INSTANCEOF   0x800 /* instanceof: MUST BE A POWER OF TWO  */