From b4481597ec8901b59a108f0b73ee1c4b57fca439 Mon Sep 17 00:00:00 2001
From: Andreas Baumann <mail@andreasbaumann.cc>
Date: Fri, 20 Aug 2021 09:56:42 +0000
Subject: cc: simple global scope and duplicate global detection

---
 miniany/cc.c    | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++------
 miniany/test1.c |  2 +-
 2 files changed, 78 insertions(+), 10 deletions(-)

diff --git a/miniany/cc.c b/miniany/cc.c
index fc253b1..8d36653 100644
--- a/miniany/cc.c
+++ b/miniany/cc.c
@@ -150,17 +150,17 @@ int getToken( )
 		case '/':
 			c = getChar( );
 			if( c == '/' ) {
-				while( c != '\n' ) {
+				while( c != EOF && c != '\n' ) {
 					c = getChar( );
 				}
 				t = getToken( );
 			} else if( c == '*' ) {
 				do {
-					while( c != '*' ) {
+					while( c != EOF && c != '*' ) {
 						c = getChar( );
 					}
 					c = getChar( );
-				} while( c != '/' );
+				} while( c != EOF && c != '/' );
 				c = getChar( );
 				t = getToken( );
 			} else {
@@ -283,14 +283,12 @@ struct Symbol {
 	struct Symbol *next;
 };
 
-struct Symbol *symbol;
-
 struct Symbol *createSymbol( char *s )
 {
 	struct Symbol *sym;
 	
 	sym = (struct Symbol *)malloc( sizeof ( struct Symbol ) );
-	sym->name = (char *)strdup( s );
+	sym->name = strdup( s );
 	sym->next = NULL;
 
 	return sym;
@@ -302,6 +300,65 @@ void freeSymbol( struct Symbol *sym )
 	free( (char *)sym );
 }
 
+struct Scope {
+	char *name;
+	struct Symbol *sym;
+};
+
+struct Scope *createScope( char *name )
+{
+	struct Scope *scope;
+	
+	scope = (struct Scope *)malloc( sizeof( struct Scope ) );
+	scope->name = strdup( name );
+	scope->sym = NULL;
+	
+	return scope;
+}
+
+void freeScope( struct Scope *scope )
+{
+	struct Symbol *sym, *next;
+	
+	free( scope->name );
+	
+	sym = scope->sym;
+	while( sym != NULL ) {
+		next = sym->next;
+		freeSymbol( sym );
+		sym = next;
+	}
+	
+	free( (char *)scope );
+}
+
+struct Scope *global_scope;
+
+struct Symbol *getSymbol( struct Scope *scope, char *name )
+{
+	struct Symbol *sym;
+	
+	sym = scope->sym;
+	while( sym != NULL ) {
+		if( strcmp( name, sym->name ) == 0 ) {
+			return sym;
+		}
+		sym = sym->next;
+	}
+	
+	return NULL;
+}
+
+void insertSymbol( struct Scope *scope, struct Symbol *sym )
+{
+	if( scope->sym == NULL ) {
+		scope->sym = sym;
+	} else {
+		sym->next = scope->sym;
+		scope->sym = sym;
+	}
+}
+
 void parseDeclaration( )
 {
 	struct Symbol *sym;
@@ -309,8 +366,18 @@ void parseDeclaration( )
 	expect( S_INT, "int" );	
 	expect( S_IDENT, "identifier" );
 	putstring( "Adding glob: " ); putstring( ident ); putnl( );
-	sym = createSymbol( ident );
-	freeSymbol( sym );
+	sym = getSymbol( global_scope, ident );
+	if( sym == NULL ) {
+		sym = createSymbol( ident );
+		insertSymbol( global_scope, sym );
+	} else {
+		printErrorHeader( );
+		putstring( "duplicate global '" );
+		putstring( ident );
+		putstring( "'" );
+		putnl( );
+		exit( EXIT_FAILURE );
+	}
 	expect( S_SEMICOLON, ";" );
 }
 
@@ -339,7 +406,7 @@ int main( int argc, char **argv )
 	row = 1;
 	pushback = 0;
 	DEBUG_SCANNER = 1;
-	symbol = NULL;
+	global_scope = createScope( "global" );
 	ident = (char *)malloc( MAX_IDENT_LEN+1 );
 
 	token = getToken( );
@@ -347,6 +414,7 @@ int main( int argc, char **argv )
 		parseStatement( );
 	}
 
+	freeScope( global_scope );
 	free( (char *)ident );
 	
 	exit( EXIT_SUCCESS );
diff --git a/miniany/test1.c b/miniany/test1.c
index ba8dd4f..94684fa 100644
--- a/miniany/test1.c
+++ b/miniany/test1.c
@@ -1,6 +1,6 @@
 /* test1 */
 
 int i;
-int i;
+int j;
 
 i = 12+25/5-2*3; // another comment
-- 
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