X-Git-Url: http://deadsoftware.ru/gitweb?a=blobdiff_plain;f=oberon.c;h=0aa8d45bf1304f6a95fe211480359d30afa7c9ef;hb=90ad7d921e60c24b11bc08cd173c0e1c80f9b06d;hp=e411c6c2fdaa455bf15fddcd54c7b94a37f3c8c3;hpb=b752043cfbb49243ca3727dbfc9be5b614a8c9c2;p=dsw-obn.git

diff --git a/oberon.c b/oberon.c
index e411c6c..0aa8d45 100644
--- a/oberon.c
+++ b/oberon.c
@@ -3,7 +3,9 @@
 #include <stdarg.h>
 #include <ctype.h>
 #include <string.h>
+
 #include "oberon.h"
+#include "generator.h"
 
 enum {
 	EOF_ = 0,
@@ -16,26 +18,34 @@ enum {
 	COLON,
 	BEGIN,
 	ASSIGN,
-	INTEGER
-};
-
-enum {
-	MODE_VAR,
-	MODE_INTEGER,
+	INTEGER,
+	TRUE,
+	FALSE,
+	LPAREN,
+	RPAREN,
+	EQUAL,
+	NEQ,
+	LESS,
+	LEQ,
+	GREAT,
+	GEQ,
+	PLUS,
+	MINUS,
+	OR,
+	STAR,
+	SLASH,
+	DIV,
+	MOD,
+	AND,
+	NOT,
+	PROCEDURE
 };
 
-typedef struct
-{
-	int mode;
-	int integer;
-	oberon_var_t * var;
-} oberon_item_t;
-
 // =======================================================================
 //   UTILS
 // ======================================================================= 
 
-static void
+void
 oberon_error(oberon_context_t * ctx, const char * fmt, ...)
 {
 	va_list ptr;
@@ -50,85 +60,141 @@ oberon_error(oberon_context_t * ctx, const char * fmt, ...)
 	exit(1);
 }
 
-static int
-oberon_item_to_type_class(oberon_context_t * ctx, oberon_item_t * item)
+// =======================================================================
+//   TABLE
+// ======================================================================= 
+
+static oberon_scope_t *
+oberon_open_scope(oberon_context_t * ctx)
 {
-	int class;
+	oberon_scope_t * scope = malloc(sizeof *scope);
+	memset(scope, 0, sizeof *scope);
 
-	if(item -> mode == MODE_INTEGER)
-	{
-		class = OBERON_TYPE_INTEGER;
-	}
-	else if(item -> mode == MODE_VAR)
-	{
-		class = item -> var -> type -> class;
-	}
-	else
-	{
-		oberon_error(ctx, "oberon_item_to_type_class: wat");
-	}
+	oberon_object_t * list = malloc(sizeof *list);
+	memset(list, 0, sizeof *list);
 
-	return class;
+	scope -> ctx = ctx;
+	scope -> list = list;
+	scope -> up = ctx -> decl;
+
+	ctx -> decl = scope;
+	return scope;
 }
 
-// =======================================================================
-//   TABLE
-// ======================================================================= 
+static void
+oberon_close_scope(oberon_scope_t * scope)
+{
+	oberon_context_t * ctx = scope -> ctx;
+	ctx -> decl = scope -> up;
+}
 
-static oberon_type_t *
-oberon_find_type(oberon_context_t * ctx, char * name)
+static oberon_object_t *
+oberon_define_object(oberon_scope_t * scope, char * name, int class)
 {
-	oberon_type_t * x = ctx -> types;
+	oberon_object_t * x = scope -> list;
 	while(x -> next && strcmp(x -> next -> name, name) != 0)
 	{
 		x = x -> next;
 	}
 
-	return x -> next;
+	if(x -> next)
+	{
+		oberon_error(scope -> ctx, "already defined");
+	}
+
+	oberon_object_t * newvar = malloc(sizeof *newvar);
+	memset(newvar, 0, sizeof *newvar);
+	newvar -> name = name;
+	newvar -> class = class;
+
+	x -> next = newvar;
+
+	return newvar;
 }
 
-static oberon_var_t *
-oberon_find_var(oberon_context_t * ctx, char * name)
+static oberon_object_t *
+oberon_find_object_in_list(oberon_object_t * list, char * name)
 {
-	oberon_var_t * x = ctx -> mod -> vars;
+	oberon_object_t * x = list;
 	while(x -> next && strcmp(x -> next -> name, name) != 0)
 	{
 		x = x -> next;
 	}
-
 	return x -> next;
 }
 
-static void
-oberon_define_var(oberon_context_t * ctx, char * name, oberon_type_t * type)
+static oberon_object_t *
+oberon_find_object(oberon_scope_t * scope, char * name)
 {
-	oberon_var_t * x = ctx -> mod -> vars;
-	while(x -> next && strcmp(x -> next -> name, name) != 0)
+	oberon_object_t * result = NULL;
+
+	oberon_scope_t * s = scope;
+	while(result == NULL && s != NULL)
 	{
-		x = x -> next;
+		result = oberon_find_object_in_list(s -> list, name);
+		s = s -> up;
 	}
 
-	if(x -> next)
+	if(result == NULL)
 	{
-		oberon_error(ctx, "already defined");
+		oberon_error(scope -> ctx, "undefined ident %s", name);
 	}
 
-	oberon_var_t * newvar = malloc(sizeof *newvar);
-	memset(newvar, 0, sizeof *newvar);
-	newvar -> name = name;
-	newvar -> type = type;
+	return result;
+}
 
-	x -> next = newvar;
+static void
+oberon_define_type(oberon_scope_t * scope, char * name, oberon_type_t * type)
+{
+	oberon_object_t * id;
+	id = oberon_define_object(scope, name, OBERON_CLASS_TYPE);
+	id -> type = type;
+	oberon_generator_init_type(scope -> ctx, type);
 }
 
-// =======================================================================
-//   GENERATOR
-// ======================================================================= 
+static oberon_type_t *
+oberon_find_type(oberon_scope_t * scope, char * name)
+{
+	oberon_object_t * x = oberon_find_object(scope, name);
+	if(x -> class != OBERON_CLASS_TYPE)
+	{
+		oberon_error(scope -> ctx, "%s not a type", name);
+	}
+
+	return x -> type;
+}
 
 static void
-oberon_generate_assign(oberon_context_t * ctx, void * src, void * dst, int size)
+oberon_define_var(oberon_scope_t * scope, char * name, oberon_type_t * type)
+{
+	oberon_object_t * var;
+	var = oberon_define_object(scope, name, OBERON_CLASS_VAR);
+	var -> type = type;
+	oberon_generator_init_var(scope -> ctx, var);
+}
+
+/*
+static oberon_object_t *
+oberon_find_var(oberon_scope_t * scope, char * name)
+{
+	oberon_object_t * x = oberon_find_object(scope, name);
+
+	if(x -> class != OBERON_CLASS_VAR)
+	{
+		oberon_error(scope -> ctx, "%s not a var", name);
+	}
+
+	return x;
+}
+*/
+
+static oberon_object_t *
+oberon_define_proc(oberon_scope_t * scope, char * name)
 {
-	printf("G: %p := %p (%i);\n", dst, src, size);
+	oberon_object_t * proc;
+	proc = oberon_define_object(scope, name, OBERON_CLASS_PROC);
+	oberon_generator_init_proc(scope -> ctx, proc);
+	return proc;
 }
 
 // =======================================================================
@@ -164,9 +230,9 @@ oberon_read_ident(oberon_context_t * ctx)
 		c = ctx -> code[i];
 	}
 
-	char * ident = malloc(len + 2);
+	char * ident = malloc(len + 1);
 	memcpy(ident, &ctx->code[ctx->code_index], len);
-	ident[len + 1] = 0;
+	ident[len] = 0;
 
 	ctx -> code_index = i;
 	ctx -> c = ctx -> code[i];
@@ -189,6 +255,30 @@ oberon_read_ident(oberon_context_t * ctx)
 	{
 		ctx -> token = BEGIN;
 	}
+	else if(strcmp(ident, "TRUE") == 0)
+	{
+		ctx -> token = TRUE;
+	}
+	else if(strcmp(ident, "FALSE") == 0)
+	{
+		ctx -> token = FALSE;
+	}
+	else if(strcmp(ident, "OR") == 0)
+	{
+		ctx -> token = OR;
+	}
+	else if(strcmp(ident, "DIV") == 0)
+	{
+		ctx -> token = DIV;
+	}
+	else if(strcmp(ident, "MOD") == 0)
+	{
+		ctx -> token = MOD;
+	}
+	else if(strcmp(ident, "PROCEDURE") == 0)
+	{
+		ctx -> token = PROCEDURE;
+	}
 }
 
 static void
@@ -225,6 +315,96 @@ oberon_skip_space(oberon_context_t * ctx)
 	}
 }
 
+static void
+oberon_read_symbol(oberon_context_t * ctx)
+{
+	int c = ctx -> c;
+	switch(c)
+	{
+		case 0:
+			ctx -> token = EOF_;
+			break;
+		case ';':
+			ctx -> token = SEMICOLON;
+			oberon_get_char(ctx);
+			break;
+		case ':':
+			ctx -> token = COLON;
+			oberon_get_char(ctx);
+			if(ctx -> c == '=')
+			{
+				ctx -> token = ASSIGN;
+				oberon_get_char(ctx);
+			}
+			break;
+		case '.':
+			ctx -> token = DOT;
+			oberon_get_char(ctx);
+			break;
+		case '(':
+			ctx -> token = LPAREN;
+			oberon_get_char(ctx);
+			break;
+		case ')':
+			ctx -> token = RPAREN;
+			oberon_get_char(ctx);
+			break;
+		case '=':
+			ctx -> token = EQUAL;
+			oberon_get_char(ctx);
+			break;
+		case '#':
+			ctx -> token = NEQ;
+			oberon_get_char(ctx);
+			break;
+		case '<':
+			ctx -> token = LESS;
+			oberon_get_char(ctx);
+			if(ctx -> c == '=')
+			{
+				ctx -> token = LEQ;
+				oberon_get_char(ctx);
+			}
+			break;
+		case '>':
+			ctx -> token = GREAT;
+			oberon_get_char(ctx);
+			if(ctx -> c == '=')
+			{
+				ctx -> token = GEQ;
+				oberon_get_char(ctx);
+			}
+			break;
+		case '+':
+			ctx -> token = PLUS;
+			oberon_get_char(ctx);
+			break;
+		case '-':
+			ctx -> token = MINUS;
+			oberon_get_char(ctx);
+			break;
+		case '*':
+			ctx -> token = STAR;
+			oberon_get_char(ctx);
+			break;
+		case '/':
+			ctx -> token = SLASH;
+			oberon_get_char(ctx);
+			break;
+		case '&':
+			ctx -> token = AND;
+			oberon_get_char(ctx);
+			break;
+		case '~':
+			ctx -> token = NOT;
+			oberon_get_char(ctx);
+			break;
+		default:
+			oberon_error(ctx, "invalid char");
+			break;
+	}
+}
+
 static void
 oberon_read_token(oberon_context_t * ctx)
 {
@@ -241,30 +421,370 @@ oberon_read_token(oberon_context_t * ctx)
 	}
 	else
 	{
-		switch(c)
+		oberon_read_symbol(ctx);
+	}
+}
+
+// =======================================================================
+//   EXPRESSION
+// =======================================================================
+
+static void oberon_expect_token(oberon_context_t * ctx, int token);
+static oberon_expr_t * oberon_expr(oberon_context_t * ctx);
+static void oberon_assert_token(oberon_context_t * ctx, int token);
+static char * oberon_assert_ident(oberon_context_t * ctx);
+
+static oberon_expr_t *
+oberon_new_operator(int op, oberon_type_t * result, oberon_expr_t * left, oberon_expr_t * right)
+{
+	oberon_oper_t * operator;
+	operator = malloc(sizeof *operator);
+	memset(operator, 0, sizeof *operator);
+
+	operator -> is_item = 0;
+	operator -> result = result;
+	operator -> op = op;
+	operator -> left = left;
+	operator -> right = right;
+
+	return (oberon_expr_t *) operator;
+}
+
+static oberon_expr_t *
+oberon_new_item(int mode, oberon_type_t * result)
+{
+	oberon_item_t * item;
+        item = malloc(sizeof *item);
+        memset(item, 0, sizeof *item);
+
+	item -> is_item = 1;
+	item -> result = result;
+	item -> mode = mode;
+
+	return (oberon_expr_t *)item;
+}
+
+static oberon_expr_t *
+oberon_make_unary_op(oberon_context_t * ctx, int token, oberon_expr_t * a)
+{
+	oberon_expr_t * expr;
+	oberon_type_t * result;
+
+	result = a -> result;
+
+	if(token == MINUS)
+	{
+		if(result -> class != OBERON_TYPE_INTEGER)
+		{
+			oberon_error(ctx, "incompatible operator type");
+		}
+
+		expr = oberon_new_operator(OP_UNARY_MINUS, result, a, NULL);
+	}
+	else if(token == NOT)
+	{
+		if(result -> class != OBERON_TYPE_BOOLEAN)
+		{
+			oberon_error(ctx, "incompatible operator type");
+		}
+
+		expr = oberon_new_operator(OP_LOGIC_NOT, result, a, NULL);
+	}
+	else
+	{
+		oberon_error(ctx, "oberon_make_unary_op: wat");
+	}
+
+	return expr;
+}
+
+static oberon_expr_t *
+oberon_factor(oberon_context_t * ctx)
+{
+	char * name;
+	oberon_object_t * var;
+	oberon_expr_t * expr;
+
+	switch(ctx -> token)
+	{
+		case IDENT:
+			name = oberon_assert_ident(ctx);
+			var = oberon_find_object(ctx -> decl, name);
+			if(var -> class == OBERON_CLASS_VAR)
+			{
+				expr = oberon_new_item(MODE_VAR, var -> type);
+			}
+			else if(var -> class == OBERON_CLASS_PROC)
+			{
+				expr = oberon_new_item(MODE_CALL, var -> type);
+			}
+			else
+			{
+				oberon_error(ctx, "invalid desinator");
+			}
+			expr -> item.var = var;
+			break;
+		case INTEGER:
+			expr = oberon_new_item(MODE_INTEGER, ctx -> int_type);
+			expr -> item.integer = ctx -> integer;
+			oberon_assert_token(ctx, INTEGER);
+			break;
+		case TRUE:
+			expr = oberon_new_item(MODE_BOOLEAN, ctx -> bool_type);
+			expr -> item.boolean = 1;
+			oberon_assert_token(ctx, TRUE);
+			break;
+		case FALSE:
+			expr = oberon_new_item(MODE_BOOLEAN, ctx -> bool_type);
+			expr -> item.boolean = 0;
+			oberon_assert_token(ctx, FALSE);
+			break;
+		case LPAREN:
+			oberon_assert_token(ctx, LPAREN);
+			expr = oberon_expr(ctx);
+			oberon_assert_token(ctx, RPAREN);
+			break;
+		case NOT:
+			oberon_assert_token(ctx, NOT);
+			expr = oberon_factor(ctx);
+			expr = oberon_make_unary_op(ctx, NOT, expr);
+			break;
+		default:
+			oberon_error(ctx, "invalid expression");
+	}
+
+	return expr;
+}
+
+/*
+ * oberon_autocast_binary_op автоматически переобразовывеат тип по след. правилам:
+ *   1. Классы обоих типов должны быть одинаковы
+ *   2. В качестве результата должен быть выбран больший тип.
+ *   3. Если размер результат не должен быть меньше чем базовый int
+ */
+
+static void
+oberon_autocast_binary_op(oberon_context_t * ctx, oberon_type_t * a, oberon_type_t * b, oberon_type_t ** result)
+{
+	if((a -> class) != (b -> class))
+	{
+		oberon_error(ctx, "incompatible types");
+	}
+
+	if((a -> size) > (b -> size))
+	{
+		*result = a;
+	}
+	else
+	{
+		*result = b;
+	}
+
+	if(((*result) -> class) == OBERON_TYPE_INTEGER)
+	{
+		if(((*result) -> size) < (ctx -> int_type -> size))
+		{
+			*result = ctx -> int_type;
+		}
+	}
+
+	/* TODO: cast types */
+}
+
+#define ITMAKESBOOLEAN(x) \
+	(((x) >= EQUAL && (x) <= GEQ) || ((x) == OR) || ((x) == AND))
+
+#define ITUSEONLYINTEGER(x) \
+	((x) >= LESS && (x) <= GEQ)
+
+#define ITUSEONLYBOOLEAN(x) \
+	(((x) == OR) || ((x) == AND))
+
+static oberon_expr_t *
+oberon_make_bin_op(oberon_context_t * ctx, int token, oberon_expr_t * a, oberon_expr_t * b)
+{
+	oberon_expr_t * expr;
+	oberon_type_t * result;
+
+	oberon_autocast_binary_op(ctx, a -> result, b -> result, &result);
+
+	if(ITMAKESBOOLEAN(token))
+	{
+		if(ITUSEONLYINTEGER(token))
+		{
+			if(a -> result -> class != OBERON_TYPE_INTEGER
+				&& b -> result -> class != OBERON_TYPE_INTEGER)
+			{
+				oberon_error(ctx, "used only with integer types");
+			}
+		}
+		else if(ITUSEONLYBOOLEAN(token))
+		{
+			if(a -> result -> class != OBERON_TYPE_BOOLEAN
+				&& b -> result -> class != OBERON_TYPE_BOOLEAN)
+			{
+				oberon_error(ctx, "used only with boolean type");
+			}
+		}
+
+		if(token == EQUAL)
+		{
+			expr = oberon_new_operator(OP_EQ, result, a, b);
+		}
+		else if(token == NEQ)
+		{
+			expr = oberon_new_operator(OP_NEQ, result, a, b);
+		}
+		else if(token == LESS)
+		{
+			expr = oberon_new_operator(OP_LSS, result, a, b);
+		}
+		else if(token == LEQ)
+		{
+			expr = oberon_new_operator(OP_LEQ, result, a, b);
+		}
+		else if(token == GREAT)
+		{
+			expr = oberon_new_operator(OP_GRT, result, a, b);
+		}
+		else if(token == GEQ)
+		{
+			expr = oberon_new_operator(OP_GEQ, result, a, b);
+		}
+		else if(token == OR)
+		{
+			expr = oberon_new_operator(OP_LOGIC_OR, result, a, b);
+		}
+		else if(token == AND)
+		{
+			expr = oberon_new_operator(OP_LOGIC_AND, result, a, b);
+		}
+		else
+		{
+			oberon_error(ctx, "oberon_make_bin_op: bool wat");
+		}
+	}
+	else
+	{
+		if(token == PLUS)
 		{
-			case 0: ctx -> token = EOF_; break;
-			case ';': ctx -> token = SEMICOLON; oberon_get_char(ctx); break;
-			case ':':
-				/****************************************************/
-				ctx -> token = COLON; oberon_get_char(ctx);
-				if(ctx -> c == '=')
-				{
-					ctx -> token = ASSIGN;
-					oberon_get_char(ctx);
-				}
-				break;
-				/****************************************************/
-			case '.': ctx -> token = DOT; oberon_get_char(ctx); break;
-			default: oberon_error(ctx, "invalid char");
+			expr = oberon_new_operator(OP_ADD, result, a, b);
+		}
+		else if(token == MINUS)
+		{
+			expr = oberon_new_operator(OP_SUB, result, a, b);
+		}
+		else if(token == STAR)
+		{
+			expr = oberon_new_operator(OP_MUL, result, a, b);
+		}
+		else if(token == SLASH)
+		{
+			expr = oberon_new_operator(OP_DIV, result, a, b);
+		}
+		else if(token == DIV)
+		{
+			expr = oberon_new_operator(OP_DIV, result, a, b);
+		}
+		else if(token == MOD)
+		{
+			expr = oberon_new_operator(OP_MOD, result, a, b);
+		}
+		else
+		{
+			oberon_error(ctx, "oberon_make_bin_op: bin wat");
 		}
 	}
+
+	return expr;
+}
+
+#define ISMULOP(x) \
+	((x) >= STAR && (x) <= AND)
+
+static oberon_expr_t *
+oberon_term_expr(oberon_context_t * ctx)
+{
+	oberon_expr_t * expr;
+
+	expr = oberon_factor(ctx);
+	while(ISMULOP(ctx -> token))
+	{
+		int token = ctx -> token;
+		oberon_read_token(ctx);
+
+		oberon_expr_t * inter = oberon_factor(ctx);
+		expr = oberon_make_bin_op(ctx, token, expr, inter);
+	}
+
+	return expr;
+}
+
+#define ISADDOP(x) \
+	((x) >= PLUS && (x) <= OR)
+
+static oberon_expr_t *
+oberon_simple_expr(oberon_context_t * ctx)
+{
+	oberon_expr_t * expr;
+
+	int minus = 0;
+	if(ctx -> token == PLUS)
+	{
+		minus = 0;
+		oberon_assert_token(ctx, PLUS);
+	}
+	else if(ctx -> token == MINUS)
+	{
+		minus = 1;
+		oberon_assert_token(ctx, MINUS);
+	}
+
+	expr = oberon_term_expr(ctx);
+	while(ISADDOP(ctx -> token))
+	{
+		int token = ctx -> token;
+		oberon_read_token(ctx);
+
+		oberon_expr_t * inter = oberon_term_expr(ctx);
+		expr = oberon_make_bin_op(ctx, token, expr, inter);
+	}
+
+	if(minus)
+	{
+		expr = oberon_make_unary_op(ctx, MINUS, expr);
+	}
+
+	return expr;
+}
+
+#define ISRELATION(x) \
+	((x) >= EQUAL && (x) <= GEQ)
+
+static oberon_expr_t *
+oberon_expr(oberon_context_t * ctx)
+{
+	oberon_expr_t * expr;
+
+	expr = oberon_simple_expr(ctx);
+	while(ISRELATION(ctx -> token))
+	{
+		int token = ctx -> token;
+		oberon_read_token(ctx);
+
+		oberon_expr_t * inter = oberon_simple_expr(ctx);
+		expr = oberon_make_bin_op(ctx, token, expr, inter);
+	}
+
+	return expr;
 }
 
 // =======================================================================
 //   PARSER
 // =======================================================================
 
+static void oberon_statement_seq(oberon_context_t * ctx);
+
 static void
 oberon_expect_token(oberon_context_t * ctx, int token)
 {
@@ -284,9 +804,8 @@ oberon_assert_token(oberon_context_t * ctx, int token)
 static char *
 oberon_assert_ident(oberon_context_t * ctx)
 {
-	char * ident;
 	oberon_expect_token(ctx, IDENT);
-	ident = ctx -> string;
+	char * ident = ctx -> string;
 	oberon_read_token(ctx);
 	return ident;
 }
@@ -295,13 +814,7 @@ static oberon_type_t *
 oberon_type(oberon_context_t * ctx)
 {
 	char * name = oberon_assert_ident(ctx);
-	oberon_type_t * type = oberon_find_type(ctx, name);
-
-	if(type == NULL)
-	{
-		oberon_error(ctx, "undefined type");
-	}
-
+	oberon_type_t * type = oberon_find_type(ctx -> decl, name);
 	return type;
 }
 
@@ -311,7 +824,53 @@ oberon_var_decl(oberon_context_t * ctx)
 	char * name = oberon_assert_ident(ctx);
 	oberon_assert_token(ctx, COLON);
 	oberon_type_t * type = oberon_type(ctx);
-	oberon_define_var(ctx, name, type);
+	oberon_define_var(ctx -> decl, name, type);
+}
+
+static void
+oberon_make_procedure_begin(oberon_context_t * ctx, char * name)
+{
+	oberon_object_t * proc;
+	proc = oberon_define_proc(ctx -> decl, name);
+
+	oberon_open_scope(ctx);
+
+	oberon_generate_begin_proc(ctx, proc);
+}
+
+static void
+oberon_make_procedure_end(oberon_context_t * ctx)
+{
+	oberon_generate_end_proc(ctx);
+
+	oberon_close_scope(ctx -> decl);
+}
+
+static void
+oberon_proc_decl(oberon_context_t * ctx)
+{
+	oberon_assert_token(ctx, PROCEDURE);
+
+	char * name;
+	name = oberon_assert_ident(ctx);
+
+	oberon_assert_token(ctx, SEMICOLON);
+
+	oberon_make_procedure_begin(ctx, name);
+	if(ctx -> token == BEGIN)
+	{
+		oberon_assert_token(ctx, BEGIN);
+		oberon_statement_seq(ctx);
+	}
+	oberon_make_procedure_end(ctx);
+
+	oberon_assert_token(ctx, END);
+	char * name2 = oberon_assert_ident(ctx);
+
+	if(strcmp(name2, name) != 0)
+	{
+		oberon_error(ctx, "procedure name not matched");
+	}
 }
 
 static void
@@ -326,71 +885,75 @@ oberon_decl_seq(oberon_context_t * ctx)
 			oberon_assert_token(ctx, SEMICOLON);
 		}
 	}
+
+	if(ctx -> token == PROCEDURE)
+	{
+		oberon_proc_decl(ctx);
+		oberon_assert_token(ctx, SEMICOLON);
+	}
 }
 
-static oberon_item_t *
-oberon_expr(oberon_context_t * ctx)
+static void
+oberon_assign(oberon_context_t * ctx, oberon_expr_t * src, oberon_expr_t * dst)
 {
-	oberon_item_t * item = malloc(sizeof *item);
-	memset(item, 0, sizeof *item);
+	if(src -> result -> class != dst -> result -> class)
+	{
+		oberon_error(ctx, "incompatible assignment types");
+	}
 
-	if(ctx -> token == IDENT)
+	if(dst -> result -> class == OBERON_TYPE_INTEGER)
 	{
-		char * name = oberon_assert_ident(ctx);
-		oberon_var_t * var = oberon_find_var(ctx, name);
-		if(var == NULL)
+		if((dst -> result -> size) < (src -> result -> size))
 		{
-			oberon_error(ctx, "undefined variable");
+			oberon_error(ctx, "incompatible assignment type size");
 		}
-		item -> mode = MODE_VAR;
-		item -> var = var;
-	}
-	else if(ctx -> token == INTEGER)
-	{
-		item -> mode = MODE_INTEGER;
-		item -> integer = ctx -> integer;
-		oberon_assert_token(ctx, INTEGER);
-	}
-	else
-	{
-		oberon_error(ctx, "invalid expression");
 	}
 
-	return item;
+	oberon_generate_assign(ctx, src, dst);
 }
 
 static void
-oberon_assign(oberon_context_t * ctx, oberon_item_t * src, oberon_item_t * dst)
+oberon_make_call(oberon_context_t * ctx, oberon_expr_t * desig)
 {
-	if(dst -> mode == MODE_INTEGER)
+	if(desig -> is_item == 0)
 	{
-		oberon_error(ctx, "invalid assignment");
+		oberon_error(ctx, "expected item");
 	}
 
-	int src_class = oberon_item_to_type_class(ctx, src);
-	int dst_class = oberon_item_to_type_class(ctx, dst);
+	if(desig -> item.mode != MODE_CALL)
+	{
+		oberon_error(ctx, "expected mode CALL");
+	}
 
-	if(src_class != dst_class)
+	if(desig -> item.var -> class != OBERON_CLASS_PROC)
 	{
-		oberon_error(ctx, "types not matched");
+		oberon_error(ctx, "only procedures can be called");
 	}
 
-	// TODO: code generation
-	oberon_generate_assign(ctx, 0, 0, 4);
+	// TODO check arguments
+
+	oberon_generate_call_proc(ctx, desig);
 }
 
 static void
 oberon_statement(oberon_context_t * ctx)
 {
-	oberon_item_t * item1;
-	oberon_item_t * item2;
+	oberon_expr_t * item1;
+	oberon_expr_t * item2;
 
 	if(ctx -> token == IDENT)
 	{
 		item1 = oberon_expr(ctx);
-		oberon_assert_token(ctx, ASSIGN);
-		item2 = oberon_expr(ctx);
-		oberon_assign(ctx, item2, item1);
+		if(ctx -> token == ASSIGN)
+		{
+			oberon_assert_token(ctx, ASSIGN);
+			item2 = oberon_expr(ctx);
+			oberon_assign(ctx, item2, item1);
+		}
+		else
+		{
+			oberon_make_call(ctx, item1);
+		}
 	}
 }
 
@@ -406,7 +969,7 @@ oberon_statement_seq(oberon_context_t * ctx)
 }
 
 static void
-oberon_parse_it(oberon_context_t * ctx)
+oberon_parse_module(oberon_context_t * ctx)
 {
 	char *name1, *name2;
 	oberon_read_token(ctx);
@@ -421,7 +984,9 @@ oberon_parse_it(oberon_context_t * ctx)
 	if(ctx -> token == BEGIN)
 	{
 		oberon_assert_token(ctx, BEGIN);
+		oberon_generate_begin_module(ctx);
 		oberon_statement_seq(ctx);
+		oberon_generate_end_module(ctx);
 	}
 
 	oberon_assert_token(ctx, END);
@@ -438,52 +1003,83 @@ oberon_parse_it(oberon_context_t * ctx)
 //   LIBRARY
 // =======================================================================
 
+static oberon_type_t *
+oberon_new_type_ptr(int class)
+{
+	oberon_type_t * x = malloc(sizeof *x);
+	memset(x, 0, sizeof *x);
+	x -> class = class;
+	return x;
+}
+
+static oberon_type_t *
+oberon_new_type_integer(int size)
+{
+	oberon_type_t * x;
+	x = oberon_new_type_ptr(OBERON_TYPE_INTEGER);
+	x -> size = size;
+	return x;
+}
+
+static oberon_type_t *
+oberon_new_type_boolean(int size)
+{
+	oberon_type_t * x;
+	x = oberon_new_type_ptr(OBERON_TYPE_BOOLEAN);
+	x -> size = size;
+	return x;
+}
+
+static void
+register_default_types(oberon_context_t * ctx)
+{
+	ctx -> int_type = oberon_new_type_integer(sizeof(int));
+	ctx -> bool_type = oberon_new_type_boolean(sizeof(int));
+
+	oberon_define_type(ctx -> world_scope, "INTEGER", ctx -> int_type);
+	oberon_define_type(ctx -> world_scope, "BOOLEAN", ctx -> bool_type);
+}
+
 oberon_context_t *
 oberon_create_context()
 {
 	oberon_context_t * ctx = malloc(sizeof *ctx);
 	memset(ctx, 0, sizeof *ctx);
 
-	oberon_type_t * types = malloc(sizeof *types);
-	memset(types, 0, sizeof *types);
+	oberon_scope_t * world_scope;
+	world_scope = oberon_open_scope(ctx);
+	ctx -> world_scope = world_scope;
+
+	oberon_generator_init_context(ctx);
+
+	register_default_types(ctx);	
 
-	ctx -> types = types;
 	return ctx;
 }
 
+void
+oberon_destroy_context(oberon_context_t * ctx)
+{
+	oberon_generator_destroy_context(ctx);
+	free(ctx);
+}
+
 oberon_module_t *
 oberon_compile_module(oberon_context_t * ctx, const char * code)
 {
 	oberon_module_t * mod = malloc(sizeof *mod);
 	memset(mod, 0, sizeof *mod);
-	oberon_var_t * vars = malloc(sizeof *vars);
-	memset(vars, 0, sizeof *vars);
 	ctx -> mod = mod;
-	ctx -> mod -> vars = vars;
-
-	oberon_init_scaner(ctx, code);
-	oberon_parse_it(ctx);
-	return mod;
-}
 
-void
-oberon_register_global_type(oberon_context_t * ctx, oberon_type_t * type)
-{
-	oberon_type_t * x = ctx -> types;
-	while(x -> next && strcmp(x -> next -> name, type -> name) != 0)
-	{
-		x = x -> next;
-	}
+	oberon_scope_t * module_scope;
+	module_scope = oberon_open_scope(ctx);
+	mod -> decl = module_scope;
 
-	if(x -> next)
-	{
-		oberon_error(ctx, "already defined");
-	}
+	oberon_init_scaner(ctx, code);
+	oberon_parse_module(ctx);
 
-	// TODO: copy type name (not a pointer)
-	oberon_type_t * newtype = malloc(sizeof *newtype);
-	memcpy(newtype, type, sizeof *newtype);
-	newtype -> next = NULL;
+	oberon_generate_code(ctx);
 
-	x -> next = newtype;
+	ctx -> mod = NULL;
+	return mod;
 }