diff options
Diffstat (limited to 'build/lexer')
| -rw-r--r-- | build/lexer | 34 |
1 files changed, 27 insertions, 7 deletions
diff --git a/build/lexer b/build/lexer index 9a0582d..1e253fd 100644 --- a/build/lexer +++ b/build/lexer @@ -7,7 +7,9 @@ #include <string> #include <iosfwd> +#include <cstddef> // size_t #include <cstdint> // uint64_t +#include <cassert> #include <exception> #include <butl/char-scanner> @@ -27,13 +29,13 @@ namespace build // pairs modes are automatically reset after the end of the line. // The variable mode is automatically reset after the name token. // - enum class lexer_mode {normal, value, variable, pairs}; + enum class lexer_mode {normal, variable, value, pairs}; class lexer: protected butl::char_scanner { public: lexer (std::istream& is, const std::string& name) - : char_scanner (is), fail (name) {} + : char_scanner (is), fail (name) {mode_.push (lexer_mode::normal);} const std::string& name () const {return fail.name_;} @@ -44,12 +46,17 @@ namespace build void mode (lexer_mode m, char pair_separator = '=') { - next_mode_ = m; + mode_.push (m); pair_separator_ = pair_separator; } + // Expire the current mode early. + // + void + expire_mode () {mode_.pop ();} + lexer_mode - mode () const {return mode_;} + mode () const {return mode_.top ();} char pair_separator () const {return pair_separator_;} @@ -93,10 +100,23 @@ namespace build private: fail_mark fail; - lexer_mode mode_ {lexer_mode::normal}; + // Currently, the maximum mode nesting is 3: {normal, value, variable}. + // + struct mode_stack + { + static const size_t max_size = 3; + + void push (lexer_mode m) {assert (n_ != max_size); d_[n_++] = m;} + void pop () {assert (n_ != 0); n_--;} + lexer_mode top () const {return d_[n_ - 1];} + + private: + size_t n_ = 0; + lexer_mode d_[max_size]; + }; + + mode_stack mode_; char pair_separator_; - lexer_mode next_mode_ {lexer_mode::normal}; // Switch to for next token. - lexer_mode prev_mode_; // Return to after current mode expires. }; } |