1 // parse.h -- Go frontend parser. -*- C++ -*-
2
3 // Copyright 2009 The Go Authors. All rights reserved.
4 // Use of this source code is governed by a BSD-style
5 // license that can be found in the LICENSE file.
6
7 #ifndef GO_PARSE_H
8 #define GO_PARSE_H
9
10 class Lex;
11 class Gogo;
12 class Named_object;
13 class Type;
14 class Typed_identifier;
15 class Typed_identifier_list;
16 class Channel_type;
17 class Function_type;
18 class Block;
19 class Expression;
20 class Expression_list;
21 class Struct_field_list;
22 class Case_clauses;
23 class Type_case_clauses;
24 class Select_clauses;
25 class Statement;
26 class Label;
27
28 // Parse the program.
29
30 class Parse
31 {
32 public:
33 Parse(Lex*, Gogo*);
34
35 // Parse a program.
36 void
37 program();
38
39 private:
40 // Precedence values.
41 enum Precedence
42 {
43 PRECEDENCE_INVALID = -1,
44 PRECEDENCE_NORMAL = 0,
45 PRECEDENCE_OROR,
46 PRECEDENCE_ANDAND,
47 PRECEDENCE_RELOP,
48 PRECEDENCE_ADDOP,
49 PRECEDENCE_MULOP
50 };
51
52 // We use this when parsing the range clause of a for statement.
53 struct Range_clause
54 {
55 // Set to true if we found a range clause.
56 bool found;
57 // The index expression.
58 Expression* index;
59 // The value expression.
60 Expression* value;
61 // The range expression.
62 Expression* range;
63
64 Range_clause()
65 : found(false), index(NULL), value(NULL), range(NULL)
66 { }
67 };
68
69 // We use this when parsing the statement at the start of a switch,
70 // in order to recognize type switches.
71 struct Type_switch
72 {
73 // Set to true if we find a type switch.
74 bool found;
75 // The variable name.
76 std::string name;
77 // The location of the variable.
78 Location location;
79 // The expression.
80 Expression* expr;
81
82 Type_switch()
83 : found(false), name(), location(Linemap::unknown_location()),
84 expr(NULL)
85 { }
86 };
87
88 // A variable defined in an enclosing function referenced by the
89 // current function.
90 class Enclosing_var
91 {
92 public:
93 Enclosing_var(Named_object* var, Named_object* in_function,
94 unsigned int index)
95 : var_(var), in_function_(in_function), index_(index)
96 { }
97
98 // We put these in a vector, so we need a default constructor.
99 Enclosing_var()
100 : var_(NULL), in_function_(NULL), index_(-1U)
101 { }
102
103 Named_object*
104 var() const
105 { return this->var_; }
106
107 Named_object*
108 in_function() const
109 { return this->in_function_; }
110
111 unsigned int
112 index() const
113 { return this->index_; }
114
115 private:
116 // The variable which is being referred to.
117 Named_object* var_;
118 // The function where the variable is defined.
119 Named_object* in_function_;
120 // The index of the field in this function's closure struct for
121 // this variable.
122 unsigned int index_;
123 };
124
125 // We store Enclosing_var entries in a set, so we need a comparator.
126 struct Enclosing_var_comparison
127 {
128 bool
129 operator()(const Enclosing_var&, const Enclosing_var&) const;
130 };
131
132 // A set of Enclosing_var entries.
133 typedef std::set<Enclosing_var, Enclosing_var_comparison> Enclosing_vars;
134
135 // Used to detect duplicate parameter/result names.
136 typedef std::map<std::string, const Typed_identifier*> Names;
137
138 // Peek at the current token from the lexer.
139 const Token*
140 peek_token();
141
142 // Consume the current token, return the next one.
143 const Token*
144 advance_token();
145
146 // Push a token back on the input stream.
147 void
148 unget_token(const Token&);
149
150 // The location of the current token.
151 Location
152 location();
153
154 // For break and continue we keep a stack of statements with
155 // associated labels (if any). The top of the stack is used for a
156 // break or continue statement with no label.
157 typedef std::vector<std::pair<Statement*, Label*> > Bc_stack;
158
159 // Parser nonterminals.
160 void identifier_list(Typed_identifier_list*);
161 Expression_list* expression_list(Expression*, bool may_be_sink,
162 bool may_be_composite_lit);
163 bool qualified_ident(std::string*, Named_object**);
164 Type* type();
165 bool type_may_start_here();
166 Type* type_name(bool issue_error);
167 Type* array_type(bool may_use_ellipsis);
168 Type* map_type();
169 Type* struct_type();
170 void field_decl(Struct_field_list*);
171 Type* pointer_type();
172 Type* channel_type();
173 void check_signature_names(const Typed_identifier_list*, Names*);
174 Function_type* signature(Typed_identifier*, Location);
175 bool parameters(Typed_identifier_list**, bool* is_varargs);
176 Typed_identifier_list* parameter_list(bool* is_varargs);
177 void parameter_decl(bool, Typed_identifier_list*, bool*, bool*, bool*);
178 bool result(Typed_identifier_list**);
179 Location block();
180 Type* interface_type(bool record);
181 void method_spec(Typed_identifier_list*);
182 void declaration();
183 bool declaration_may_start_here();
184 void decl(void (Parse::*)());
185 void list(void (Parse::*)(), bool);
186 void const_decl();
187 void const_spec(int, Type**, Expression_list**);
188 void update_references(Expression**);
189 void type_decl();
190 void type_spec();
191 void var_decl();
192 void var_spec();
193 void init_vars(const Typed_identifier_list*, Type*, Expression_list*,
194 bool is_coloneq, std::vector<std::string>*, Location);
195 bool init_vars_from_call(const Typed_identifier_list*, Type*, Expression*,
196 bool is_coloneq, Location);
197 bool init_vars_from_map(const Typed_identifier_list*, Type*, Expression*,
198 bool is_coloneq, Location);
199 bool init_vars_from_receive(const Typed_identifier_list*, Type*,
200 Expression*, bool is_coloneq, Location);
201 bool init_vars_from_type_guard(const Typed_identifier_list*, Type*,
202 Expression*, bool is_coloneq,
203 Location);
204 Named_object* init_var(const Typed_identifier&, Type*, Expression*,
205 bool is_coloneq, bool type_from_init, bool* is_new,
206 Expression_list* vars, Expression_list* vals);
207 Named_object* create_dummy_global(Type*, Expression*, Location);
208 void finish_init_vars(Expression_list* vars, Expression_list* vals,
209 Location);
210 void simple_var_decl_or_assignment(const std::string&, Location,
211 bool may_be_composite_lit,
212 Range_clause*, Type_switch*);
213 void function_decl();
214 Typed_identifier* receiver();
215 Expression* operand(bool may_be_sink, bool *is_parenthesized);
216 Expression* enclosing_var_reference(Named_object*, Named_object*,
217 bool may_be_sink, Location);
218 Expression* composite_lit(Type*, int depth, Location);
219 Expression* function_lit();
220 Expression* create_closure(Named_object* function, Enclosing_vars*,
221 Location);
222 Expression* primary_expr(bool may_be_sink, bool may_be_composite_lit,
223 bool* is_type_switch, bool* is_parenthesized);
224 Expression* selector(Expression*, bool* is_type_switch);
225 Expression* index(Expression*);
226 Expression* call(Expression*);
227 Expression* expression(Precedence, bool may_be_sink,
228 bool may_be_composite_lit, bool* is_type_switch,
229 bool *is_parenthesized);
230 bool expression_may_start_here();
231 Expression* unary_expr(bool may_be_sink, bool may_be_composite_lit,
232 bool* is_type_switch, bool* is_parenthesized);
233 Type* reassociate_chan_direction(Channel_type*, Location);
234 Expression* qualified_expr(Expression*, Location);
235 Expression* id_to_expression(const std::string&, Location, bool, bool);
236 void statement(Label*);
237 bool statement_may_start_here();
238 void labeled_stmt(const std::string&, Location);
239 Expression* simple_stat(bool, bool*, Range_clause*, Type_switch*);
240 bool simple_stat_may_start_here();
241 void statement_list();
242 bool statement_list_may_start_here();
243 void expression_stat(Expression*);
244 void send_stmt(Expression*, bool may_be_composite_lit);
245 void inc_dec_stat(Expression*);
246 void assignment(Expression*, bool may_be_composite_lit, Range_clause*);
247 void tuple_assignment(Expression_list*, bool may_be_composite_lit,
248 Range_clause*);
249 void send();
250 void go_or_defer_stat();
251 void return_stat();
252 void if_stat();
253 void switch_stat(Label*);
254 Statement* expr_switch_body(Label*, Expression*, Location);
255 void expr_case_clause(Case_clauses*, bool* saw_default);
256 Expression_list* expr_switch_case(bool*);
257 Statement* type_switch_body(Label*, const Type_switch&, Location);
258 void type_case_clause(const std::string&, Expression*, Type_case_clauses*,
259 bool* saw_default, std::vector<Named_object*>*);
260 void type_switch_case(std::vector<Type*>*, bool*);
261 void select_stat(Label*);
262 void comm_clause(Select_clauses*, bool* saw_default);
263 bool comm_case(bool*, Expression**, Expression**, Expression**,
264 std::string*, std::string*, bool*);
265 bool send_or_recv_stmt(bool*, Expression**, Expression**, Expression**,
266 std::string*, std::string*);
267 void for_stat(Label*);
268 void for_clause(Expression**, Block**);
269 void range_clause_decl(const Typed_identifier_list*, Range_clause*);
270 void range_clause_expr(const Expression_list*, Range_clause*);
271 void push_break_statement(Statement*, Label*);
272 void push_continue_statement(Statement*, Label*);
273 void pop_break_statement();
274 void pop_continue_statement();
275 Statement* find_bc_statement(const Bc_stack*, const std::string&);
276 void break_stat();
277 void continue_stat();
278 void goto_stat();
279 void package_clause();
280 void import_decl();
281 void import_spec();
282
283 // Check for unused compiler directives.
284 void check_directives();
285
286 // Skip past an error looking for a semicolon or OP. Return true if
287 // all is well, false if we found EOF.
288 bool
289 skip_past_error(Operator op);
290
291 // Verify that an expression is not a sink, and return either the
292 // expression or an error.
293 Expression*
294 verify_not_sink(Expression*);
295
296 // Return the statement associated with a label in a Bc_stack, or
297 // NULL.
298 Statement*
299 find_bc_statement(const Bc_stack*, const std::string&) const;
300
301 // Mark a variable as used.
302 void
303 mark_var_used(Named_object*);
304
305 // The lexer output we are parsing.
306 Lex* lex_;
307 // The current token.
308 Token token_;
309 // A token pushed back on the input stream.
310 Token unget_token_;
311 // Whether unget_token_ is valid.
312 bool unget_token_valid_;
313 // Whether the function we are parsing had errors in the signature.
314 bool is_erroneous_function_;
315 // The code we are generating.
316 Gogo* gogo_;
317 // A stack of statements for which break may be used.
318 Bc_stack* break_stack_;
319 // A stack of statements for which continue may be used.
320 Bc_stack* continue_stack_;
321 // References from the local function to variables defined in
322 // enclosing functions.
323 Enclosing_vars enclosing_vars_;
324 };
325
326
327 #endif // !defined(GO_PARSE_H)