added stacking scopes

3 files changed, 45 insertions, 12 deletions

diff --git a/minie/TODOS b/minie/TODOS
index 0d53087..d925789 100644
--- a/minie/TODOS
+++ b/minie/TODOS
@@ -227,6 +227,8 @@ design
 Scanner class or struct vs. OPS module containing all variables. all modules
 in the Oberon compiler act as singletons.
 
+nested procedures
+
 links
 -----
 
diff --git a/minie/e2c.c b/minie/e2c.c
index da59c30..8108502 100644
--- a/minie/e2c.c
+++ b/minie/e2c.c
@@ -592,6 +592,13 @@ struct SymbolTable {
 };
 
 static SymbolTable symbols;
+static SymbolTable *current_scope = &symbols;
+
+static void init_symboltable( SymbolTable *table, SymbolTable *parent )
+{
+	table->nof_symbols = 0;
+	table->parent = parent;
+}
 
 static void insert_symbol( SymbolTable *table, Type type, char *name )
 {
@@ -601,19 +608,25 @@ static void insert_symbol( SymbolTable *table, Type type, char *name )
 	
 	table->symbols[table->nof_symbols] = type;
 	strncpy( table->symbols[table->nof_symbols].name, name, MAX_IDENT_LEN );
-	
+
 	table->nof_symbols++;
 }
 
 static Type get_symbol_type( SymbolTable *table, char *name )
 {
 	int i;
-	
+
+	/* search in table of currect scope */
 	for( i = 0; i < table->nof_symbols; i++ ) {
 		if( strcmp( table->symbols[i].name, name ) == 0 ) {
 			return table->symbols[i];
 		}
 	}
+
+	/* traverse stack of parent symbol tables */
+	if( table->parent != NULL ) {
+		return get_symbol_type( table->parent, name );
+	}
 	
 	Abort( "Unknown symbol '%s'", name );
 }
@@ -655,7 +668,7 @@ static int length( char *name )
 {
 	Type type;
 	
-	type = get_symbol_type( &symbols, name );
+	type = get_symbol_type( current_scope, name );
 	if( type.type == TYPE_ARRAY ) {
 		return type.details.array.len;
 	} else {
@@ -784,6 +797,8 @@ static void prologue( void )
 "		return c;" \
 "	}" \
 "}" ); 
+
+	init_symboltable( &symbols, NULL );
 	
 	register_internal_functions( );
 	register_internal_constants( );
@@ -851,7 +866,7 @@ static void factor( void )
 		sym = getSym( );
 	} else if( sym == S_ident ) {
 		qualident( );
-		type = get_symbol_type( &symbols, varName );
+		type = get_symbol_type( current_scope, varName );
 		if( type.type == TYPE_FUNCTION ) {
 			parameterList( );
 		} else if( type.type == TYPE_CONSTANT ) {
@@ -955,7 +970,7 @@ static void selector( void )
 	selected_array = 0;
 	if( sym == S_lbracket ) {
 		Expect( S_lbracket );
-		type = get_symbol_type( &symbols, varName );
+		type = get_symbol_type( current_scope, varName );
 		if( type.type != TYPE_ARRAY ) {
 			Abort( "Selecting element of non-array" );
 		}
@@ -976,7 +991,7 @@ static void assignment( void )
 	/* left hand side */
 	/* precondition: qualident has been already parsed outside */
 	selector( );
-	type = get_symbol_type( &symbols, varName );
+	type = get_symbol_type( current_scope, varName );
 		 
 	/* x := ( a+ b )- 3;	-> x = (a+b)-3;
 	 * s1 := s2;         	-> strncpy( s2, s1, length( s2 ) );
@@ -1181,7 +1196,7 @@ static void statement( void )
 			parameterList( );
 			emitLn( ";" );
 		} else {
-			Type type = get_symbol_type( &symbols, varName );
+			Type type = get_symbol_type( current_scope, varName );
 			if( type.type == TYPE_FUNCTION ) {
 				/* procedure call without parameter */
 				/* TODO: check number of parameter and return value to be 0 */
@@ -1310,7 +1325,7 @@ static void variableDeclaration( void )
 	sym = getSym( );
 	Expect( S_colon );
 	type( );
-	insert_symbol( &symbols, lastType, varName );
+	insert_symbol( current_scope, lastType, varName );
 	if( lastType.type == TYPE_ARRAY ) {
 		/* TODO: this works for now, though it's not correct */
 		emitLn( "static %s %s[%d];",
@@ -1351,6 +1366,9 @@ static void procedureDeclaration( void )
 {
 	char return_type[MAX_IDENT_LEN];
 	Type funcType;
+	SymbolTable locals;
+
+	init_symboltable( &locals, current_scope );
 	
 	funcType.type = TYPE_FUNCTION;	
 	funcType.details.function.internal = 0;
@@ -1385,6 +1403,8 @@ static void procedureDeclaration( void )
 					type( );
 					funcType.details.function.params[funcType.details.function.len]->type = lastType.type;
 				}
+				insert_symbol( &locals, *funcType.details.function.params[funcType.details.function.len],
+					funcType.details.function.params[funcType.details.function.len]->name );
 				funcType.details.function.len++;
 			} while( sym == S_comma );
 		}
@@ -1405,7 +1425,8 @@ static void procedureDeclaration( void )
 	}
 	Expect( S_semicolon );
 		
-	insert_symbol( &symbols, funcType, procName );
+	insert_symbol( current_scope, funcType, procName );
+	current_scope = &locals;
 	
 	emit( "%s %s( ", return_type, procName );
 	if( funcType.details.function.len == 0 ) {
@@ -1419,12 +1440,16 @@ static void procedureDeclaration( void )
 		}
 	}
 	emitLn( ") {" );
+
 	if( sym == S_var ) {
 		variableBlock( );
 	}
 	if( sym == S_begin ) {
 		statementBlock( );
 	}
+
+	current_scope = current_scope->parent;
+
 	emitLn( "}" );
 }
 
diff --git a/minie/ec.e b/minie/ec.e
index 1dd1221..57d5a55 100644
--- a/minie/ec.e
+++ b/minie/ec.e
@@ -44,16 +44,20 @@ begin
 	end
 end
 
+procedure getSym : integer;
+begin
+end
+
 (* parser *)
 	
 procedure Expect( expect : integer );
-(* TODO: Error line 51, pos 22: Unknown symbol 'expect': add symbol to local scope
-   and remove it at end of scope/procedure *)
 begin
 	if ( sym = expect ) do
-		sym = getSym( );
+		sym := getSym( );
 	else
+		(* TODO: symtable names
 		Abort( "Expected symbol", symname[expect] );
+		*)
 	end
 end
 
@@ -72,7 +76,9 @@ end
 
 procedure doModule;
 begin
+	(* TODO: unkown symbol of state CONST
 	Expect( S_module );
+	*)
 	look := getChar( );
 	while ( look <> char( 0 ) ) do
 		if not isWhite( look ) do