add NEXT statement

Author: ghewgill

ast.h

@@ -1083,6 +1083,20 @@ class ExitStatement: public Statement {
     ExitStatement &operator=(const ExitStatement &);
 };
 
+class NextStatement: public Statement {
+public:
+    NextStatement(int line, unsigned int loop_id): Statement(line), loop_id(loop_id) {}
+
+    const unsigned int loop_id;
+
+    virtual void generate_code(Emitter &emitter) const;
+
+    virtual std::string text() const { return "NextStatement(...)"; }
+private:
+    NextStatement(const NextStatement &);
+    NextStatement &operator=(const NextStatement &);
+};
+
 class Function: public Variable {
 public:
     Function(const std::string &name, const Type *returntype, Scope *scope, const std::vector<FunctionParameter *> &params): Variable(name, makeFunctionType(returntype, params)), scope(scope), params(params), entry_label(UINT_MAX), statements() {}

compiler.cpp

@@ -16,8 +16,15 @@ class Emitter {
         std::vector<unsigned int> fixups;
         unsigned int target;
     };
+    class LoopLabels {
+    public:
+        LoopLabels(): exit(nullptr), next(nullptr) {}
+        LoopLabels(Label *exit, Label *next): exit(exit), next(next) {}
+        Label *exit;
+        Label *next;
+    };
 public:
-    Emitter(DebugInfo *debug): code(), strings(), globals(), functions(), exit_label(), debug_info(debug) {}
+    Emitter(DebugInfo *debug): code(), strings(), globals(), functions(), loop_labels(), debug_info(debug) {}
     void emit(unsigned char b);
     void emit_uint32(uint32_t value);
     void emit(unsigned char b, uint32_t value);
@@ -31,16 +38,17 @@ class Emitter {
     Label create_label();
     void emit_jump(unsigned char b, Label &label);
     void jump_target(Label &label);
-    void add_exit_label(unsigned int loop_id, Label &label);
-    void remove_exit_label(unsigned int loop_id);
+    void add_loop_labels(unsigned int loop_id, Label &exit, Label &next);
+    void remove_loop_labels(unsigned int loop_id);
     Label &get_exit_label(unsigned int loop_id);
+    Label &get_next_label(unsigned int loop_id);
     void debug_line(int line);
 private:
     std::vector<unsigned char> code;
     std::vector<std::string> strings;
     std::vector<std::string> globals;
     std::vector<Label> functions;
-    std::map<size_t, Label *> exit_label;
+    std::map<size_t, LoopLabels> loop_labels;
     DebugInfo *debug_info;
 private:
     Emitter(const Emitter &);
@@ -156,22 +164,30 @@ void Emitter::jump_target(Label &label)
     }
 }
 
-void Emitter::add_exit_label(unsigned int loop_id, Label &label)
+void Emitter::add_loop_labels(unsigned int loop_id, Label &exit, Label &next)
 {
-    exit_label[loop_id] = &label;
+    loop_labels[loop_id] = LoopLabels(&exit, &next);
 }
 
-void Emitter::remove_exit_label(unsigned int loop_id)
+void Emitter::remove_loop_labels(unsigned int loop_id)
 {
-    exit_label.erase(loop_id);
+    loop_labels.erase(loop_id);
 }
 
 Emitter::Label &Emitter::get_exit_label(unsigned int loop_id)
 {
-    if (exit_label.find(loop_id) == exit_label.end()) {
+    if (loop_labels.find(loop_id) == loop_labels.end()) {
+        internal_error("loop_id not found");
+    }
+    return *loop_labels[loop_id].exit;
+}
+
+Emitter::Label &Emitter::get_next_label(unsigned int loop_id)
+{
+    if (loop_labels.find(loop_id) == loop_labels.end()) {
         internal_error("loop_id not found");
     }
-    return *exit_label[loop_id];
+    return *loop_labels[loop_id].next;
 }
 
 void Emitter::debug_line(int line)
@@ -740,14 +756,14 @@ void WhileStatement::generate_code(Emitter &emitter) const
     emitter.jump_target(top);
     condition->generate(emitter);
     auto skip = emitter.create_label();
-    emitter.add_exit_label(loop_id, skip);
     emitter.emit_jump(JF, skip);
+    emitter.add_loop_labels(loop_id, skip, top);
     for (auto stmt: statements) {
         stmt->generate(emitter);
     }
     emitter.emit_jump(JUMP, top);
     emitter.jump_target(skip);
-    emitter.remove_exit_label(loop_id);
+    emitter.remove_loop_labels(loop_id);
 }
 
 void CaseStatement::generate_code(Emitter &emitter) const
@@ -824,8 +840,8 @@ void CaseStatement::RangeWhenCondition::generate(Emitter &emitter) const
 void ForStatement::generate_code(Emitter &emitter) const
 {
     auto skip = emitter.create_label();
-    emitter.add_exit_label(loop_id, skip);
     auto loop = emitter.create_label();
+    auto next = emitter.create_label();
 
     start->generate(emitter);
     var->generate_store(emitter);
@@ -836,25 +852,33 @@ void ForStatement::generate_code(Emitter &emitter) const
     emitter.emit(GEN);
     emitter.emit_jump(JF, skip);
 
+    emitter.add_loop_labels(loop_id, skip, next);
+
     for (auto stmt: statements) {
         stmt->generate(emitter);
     }
 
+    emitter.jump_target(next);
     emitter.emit(PUSHN, number_from_uint32(1));
     var->generate_load(emitter);
     emitter.emit(ADDN);
     var->generate_store(emitter);
     emitter.emit_jump(JUMP, loop);
 
     emitter.jump_target(skip);
-    emitter.remove_exit_label(loop_id);
+    emitter.remove_loop_labels(loop_id);
 }
 
 void ExitStatement::generate_code(Emitter &emitter) const
 {
     emitter.emit_jump(JUMP, emitter.get_exit_label(loop_id));
 }
 
+void NextStatement::generate_code(Emitter &emitter) const
+{
+    emitter.emit_jump(JUMP, emitter.get_next_label(loop_id));
+}
+
 void Scope::predeclare(Emitter &emitter) const
 {
     for (auto n: names) {

lexer.cpp

@@ -72,6 +72,7 @@ std::string Token::tostring() const
         case DOTDOT:      s << "DOTDOT"; break;
         case EXTERNAL:    s << "EXTERNAL"; break;
         case EXIT:        s << "EXIT"; break;
+        case NEXT:        s << "NEXT"; break;
     }
     s << ">";
     return s.str();
@@ -192,6 +193,7 @@ std::vector<Token> tokenize(const std::string &source)
             else if (t.text == "WHEN") t.type = WHEN;
             else if (t.text == "EXTERNAL") t.type = EXTERNAL;
             else if (t.text == "EXIT") t.type = EXIT;
+            else if (t.text == "NEXT") t.type = NEXT;
         } else if (isdigit(c)) {
             t.type = NUMBER;
             if (c == '0' && (i+1 < source.length()) && source.at(i+1) != '.' && tolower(source.at(i+1)) != 'e' && not isdigit(source.at(i+1))) {

lexer.h

@@ -66,6 +66,7 @@ enum TokenType {
     DOTDOT,
     EXTERNAL,
     EXIT,
+    NEXT,
 };
 
 class Token {

parser.cpp

@@ -52,6 +52,7 @@ class Parser {
     const Statement *parseCaseStatement(Scope *scope, int line);
     const Statement *parseForStatement(Scope *scope, int line);
     const Statement *parseExitStatement(Scope *scope, int line);
+    const Statement *parseNextStatement(Scope *scope, int line);
     const Statement *parseImport(Scope *scope);
     const Statement *parseStatement(Scope *scope);
     const Program *parse();
@@ -1386,6 +1387,25 @@ const Statement *Parser::parseExitStatement(Scope *, int line)
     error(2137, tokens[i-1], "no matching loop found in current scope");
 }
 
+const Statement *Parser::parseNextStatement(Scope *, int line)
+{
+    ++i;
+    if (tokens[i].type != WHILE
+     && tokens[i].type != FOR) {
+        error(2144, tokens[i], "loop type expected");
+    }
+    TokenType type = tokens[i].type;
+    ++i;
+    if (not loops.empty()) {
+        for (auto j = loops.top().rbegin(); j != loops.top().rend(); ++j) {
+            if (j->first == type) {
+                return new NextStatement(line, j->second);
+            }
+        }
+    }
+    error(2145, tokens[i-1], "no matching loop found in current scope");
+}
+
 const Statement *Parser::parseImport(Scope *scope)
 {
     ++i;
@@ -1424,6 +1444,8 @@ const Statement *Parser::parseStatement(Scope *scope)
         return parseForStatement(scope, line);
     } else if (tokens[i].type == EXIT) {
         return parseExitStatement(scope, line);
+    } else if (tokens[i].type == NEXT) {
+        return parseNextStatement(scope, line);
     } else if (tokens[i].type == IDENTIFIER) {
         const VariableReference *ref = parseVariableReference(scope);
         if (tokens[i].type == ASSIGN) {

t/errors/S2144.simple

@@ -0,0 +1,8 @@
+VAR a: Number
+
+FOR a IN 1 TO 10 DO
+    print(str(a))
+    IF ((a MOD 5) = 0) THEN
+         NEXT
+    END IF
+NEXT

t/errors/S2145.simple

@@ -0,0 +1,8 @@
+VAR a: Number
+
+FOR a IN 1 TO 10 DO
+    print(str(a))
+    IF ((a MOD 5) = 0) THEN
+         NEXT WHILE
+    END IF
+NEXT