FLANG
stmt-parser.h
1//===-- lib/Parser/stmt-parser.h --------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef FORTRAN_PARSER_STMT_PARSER_H_
10#define FORTRAN_PARSER_STMT_PARSER_H_
11
12// Basic parsing of statements.
13
14#include "basic-parsers.h"
15#include "token-parsers.h"
16
17namespace Fortran::parser {
18
19// statement(p) parses Statement<P> for some statement type P that is the
20// result type of the argument parser p, while also handling labels and
21// end-of-statement markers.
22
23// R611 label -> digit [digit]...
24constexpr auto label{space >> digitString64 / spaceCheck};
25
26template <typename PA>
27inline constexpr auto unterminatedStatement(const PA &p) {
28 return skipStuffBeforeStatement >>
29 sourced(construct<Statement<typename PA::resultType>>(
30 maybe(label / space), p));
31}
32
33constexpr auto atEndOfStmt{space >>
34 withMessage("expected end of statement"_err_en_US, lookAhead(";\n"_ch))};
35constexpr auto checkEndOfKnownStmt{recovery(atEndOfStmt, SkipTo<'\n'>{})};
36
37constexpr auto endOfLine{consumedAllInput ||
38 withMessage("expected end of line"_err_en_US, "\n"_ch >> ok)};
39
40constexpr auto semicolons{";"_ch >> skipMany(";"_tok) / space / maybe("\n"_ch)};
41constexpr auto endOfStmt{
42 space >> withMessage("expected end of statement"_err_en_US,
43 semicolons || endOfLine)};
44constexpr auto skipToNextLineIfAny{consumedAllInput || SkipPast<'\n'>{}};
45constexpr auto forceEndOfStmt{recovery(endOfStmt, skipToNextLineIfAny)};
46
47template <typename PA> inline constexpr auto statement(const PA &p) {
48 return unterminatedStatement(p) / endOfStmt;
49}
50
51// unlabeledStatement() is basically statement() for those few situations
52// in Fortran where a statement cannot have a label.
53template <typename PA> inline constexpr auto unlabeledStatement(const PA &p) {
54 return space >>
56}
57
58// This unambiguousStatement() variant of statement() provides better error
59// recovery for contexts containing statements that might have trailing
60// garbage, but it must be used only when no instance of the statement in
61// question could also be a legal prefix of some other statement that might
62// be valid at that point. It only makes sense to use this within "some()"
63// or "many()" so as to not end the list of statements.
64template <typename PA> inline constexpr auto unambiguousStatement(const PA &p) {
65 return unterminatedStatement(p) / forceEndOfStmt;
66}
67
68constexpr auto ignoredStatementPrefix{
69 skipStuffBeforeStatement >> maybe(label) >> maybe(name / ":") >> space};
70
71// Error recovery within a statement() call: skip *to* the end of the line,
72// unless at an END or CONTAINS statement.
73constexpr auto inStmtErrorRecovery{!"END"_tok >> !"CONTAINS"_tok >>
74 (consumedAllInput || SkipTo<'\n'>{}) >> construct<ErrorRecovery>()};
75
76// Error recovery within statement sequences: skip *past* the end of the line,
77// but not over an END or CONTAINS statement.
78constexpr auto skipStmtErrorRecovery{!"END"_tok >> !"CONTAINS"_tok >>
79 (consumedAllInput || SkipPast<'\n'>{}) >> construct<ErrorRecovery>()};
80
81// Error recovery across statements: skip the line, unless it looks
82// like it might end the containing construct.
83constexpr auto stmtErrorRecoveryStart{ignoredStatementPrefix};
84constexpr auto skipBadLine{skipToNextLineIfAny >> construct<ErrorRecovery>()};
85constexpr auto executionPartErrorRecovery{stmtErrorRecoveryStart >>
86 !"END"_tok >> !"CONTAINS"_tok >> !"ELSE"_tok >> !"CASE"_tok >>
87 !"TYPE IS"_tok >> !"CLASS"_tok >> !"RANK"_tok >>
88 !("!$ACC "_sptok >> "END"_tok) >>
89 !("!$OMP "_sptok >> ("END"_tok || "SECTION"_id)) >> skipBadLine};
90
91// END statement error recovery
92constexpr auto missingOptionalName{pure<std::optional<Name>>()};
93constexpr auto noNameEnd{"END" >> missingOptionalName};
94
95// For unrecognizable construct END statements. Be sure to not consume
96// a program unit's END statement.
97constexpr auto progUnitEndStmt{consumedAllInput ||
98 "END" >> (lookAhead("\n"_ch) || "SUBROUTINE"_tok || "FUNCTION"_tok ||
99 "PROCEDURE"_tok || "MODULE"_tok || "SUBMODULE"_tok ||
100 "PROGRAM"_tok || "BLOCK DATA"_tok)};
101constexpr auto constructEndStmtErrorRecovery{
102 !progUnitEndStmt >> ("END"_tok >> SkipTo<'\n'>{} || ok)};
103constexpr auto namedConstructEndStmtErrorRecovery{
104 constructEndStmtErrorRecovery >> missingOptionalName};
105
106constexpr auto progUnitEndStmtErrorRecovery{
107 many(!"END"_tok >> SkipPast<'\n'>{}) >>
108 maybe("END"_tok >> SkipTo<'\n'>{}) >> missingOptionalName};
109
110constexpr auto beginDirective{skipStuffBeforeStatement >> "!"_ch};
111constexpr auto endDirective{space >> endOfLine};
112
113} // namespace Fortran::parser
114#endif // FORTRAN_PARSER_STMT_PARSER_H_
Definition check-expression.h:19
Definition token-parsers.h:559
Definition token-parsers.h:575
Definition parse-tree.h:355
Definition parse-tree.h:350