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Diffstat (limited to 'build2/parser.hxx')
| -rw-r--r-- | build2/parser.hxx | 593 |
1 files changed, 593 insertions, 0 deletions
diff --git a/build2/parser.hxx b/build2/parser.hxx new file mode 100644 index 0000000..85da4e5 --- /dev/null +++ b/build2/parser.hxx @@ -0,0 +1,593 @@ +// file : build2/parser.hxx -*- C++ -*- +// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd +// license : MIT; see accompanying LICENSE file + +#ifndef BUILD2_PARSER_HXX +#define BUILD2_PARSER_HXX + +#include <stack> + +#include <build2/types.hxx> +#include <build2/utility.hxx> + +#include <build2/spec.hxx> +#include <build2/lexer.hxx> +#include <build2/token.hxx> +#include <build2/variable.hxx> +#include <build2/diagnostics.hxx> + +namespace build2 +{ + class scope; + class target; + + class parser + { + public: + // If boot is true, then we are parsing bootstrap.build and modules + // should only be bootstrapped. + // + parser (bool boot = false): fail ("error", &path_), boot_ (boot) {} + + // Issue diagnostics and throw failed in case of an error. + // + void + parse_buildfile (istream&, const path& name, scope& root, scope& base); + + buildspec + parse_buildspec (istream&, const path& name); + + token + parse_variable (lexer&, scope&, const variable&, token_type kind); + + pair<value, token> + parse_variable_value (lexer&, scope&, const dir_path*, const variable&); + + names + parse_export_stub (istream& is, const path& p, scope& r, scope& b) + { + parse_buildfile (is, p, r, b); + return move (export_value_); + } + + // Recursive descent parser. + // + protected: + + // Pattern expansion mode. + // + enum class pattern_mode + { + ignore, // Treat as ordinary names. + detect, // Ignore pair/dir/type if the first name is a pattern. + expand // Expand to ordinary names. + }; + + // If one is true then parse a single (logical) line (logical means it + // can actually be several lines, e.g., an if-block). Return false if + // nothing has been parsed (i.e., we are on the same token). + // + // Note that after this function returns, the token is the first token on + // the next line (or eos). + // + bool + parse_clause (token&, token_type&, bool one = false); + + void + parse_assert (token&, token_type&); + + void + parse_print (token&, token_type&); + + void + parse_source (token&, token_type&); + + void + parse_include (token&, token_type&); + + void + parse_import (token&, token_type&); + + void + parse_export (token&, token_type&); + + void + parse_using (token&, token_type&); + + void + parse_define (token&, token_type&); + + void + parse_if_else (token&, token_type&); + + void + parse_variable (token&, token_type&, const variable&, token_type); + + string + parse_variable_name (names&&, const location&); + + // Note: calls attributes_push() that the caller must pop. + // + value + parse_variable_value (token&, token_type&); + + void + apply_variable_attributes (const variable&); + + void + apply_value_attributes (const variable*, // Optional. + value& lhs, + value&& rhs, + token_type assign_kind); + + // Return the value pack (values can be NULL/typed). Note that for an + // empty eval context ('()' potentially with whitespaces in between) the + // result is an empty pack, not a pack of one empty. + // + values + parse_eval (token&, token_type&, pattern_mode); + + values + parse_eval_comma (token&, token_type&, pattern_mode, bool = false); + + value + parse_eval_ternary (token&, token_type&, pattern_mode, bool = false); + + value + parse_eval_or (token&, token_type&, pattern_mode, bool = false); + + value + parse_eval_and (token&, token_type&, pattern_mode, bool = false); + + value + parse_eval_comp (token&, token_type&, pattern_mode, bool = false); + + value + parse_eval_value (token&, token_type&, pattern_mode, bool = false); + + // Attributes stack. We can have nested attributes, for example: + // + // x = [bool] ([uint64] $x == [uint64] $y) + // + // In this example we only apply the value attributes after evaluating + // the context, which has its own attributes. + // + struct attributes + { + bool has; // Has attributes flag. + location loc; // Start of attributes location. + vector<pair<string, string>> ats; // Attributes. + + explicit operator bool () const {return has;} + }; + + // Push a new entry into the attributes_ stack. If the next token is '[' + // parse the attribute sequence until ']' setting the 'has' flag and + // storing the result on the stack. Then get the next token and, if + // standalone is false, verify it is not newline/eos (i.e., there is + // something after it). Return the indication of whether there are + // any attributes and their location. + // + // Note that during pre-parsing nothing is pushed into the stack and + // the returned attributes object indicates there are no attributes. + // + pair<bool, location> + attributes_push (token&, token_type&, bool standalone = false); + + attributes + attributes_pop () + { + assert (!pre_parse_); + attributes r (move (attributes_.top ())); + attributes_.pop (); + return r; + } + + attributes& + attributes_top () {return attributes_.top ();} + + // If chunk is true, then parse the smallest but complete, name-wise, + // chunk of input. Note that in this case you may still end up with + // multiple names, for example, {foo bar} or $foo. In the pre-parse mode + // always return empty list of names. + // + // The what argument is used in diagnostics (e.g., "expected <what> + // instead of ...". + // + // The separators argument specifies the special characters to recognize + // inside the name. These can be the directory separators and the '%' + // project separator. Note that even if it is NULL, the result may still + // contain non-simple names due to variable expansions. + // + + static const string name_separators; + + names + parse_names (token& t, token_type& tt, + pattern_mode pmode, + bool chunk = false, + const char* what = "name", + const string* separators = &name_separators) + { + names ns; + parse_names (t, tt, + ns, + pmode, + chunk, + what, + separators, + 0, + nullopt, nullptr, nullptr); + return ns; + } + + // As above but return the result as a value, which can be typed and NULL. + // + value + parse_value (token& t, token_type& tt, + pattern_mode pmode, + const char* what = "name", + const string* separators = &name_separators, + bool chunk = false) + { + names ns; + auto r (parse_names (t, tt, + ns, + pmode, + chunk, + what, + separators, + 0, + nullopt, nullptr, nullptr)); + + value v (r.type); // Potentially typed NULL value. + + // This should not fail since we are typing the result of reversal from + // the typed value. + // + if (r.not_null) + v.assign (move (ns), nullptr); + + return v; + } + + // Append names and return the indication if the parsed value is not NULL + // and whether it is typed (and whether it is a pattern if pattern_mode is + // detect). + // + // You may have noticed that what we return here is essentially a value + // and doing it this way (i.e., reversing it to untyped names and + // returning its type so that it can potentially be "typed back") is kind + // of backwards. The reason we are doing it this way is because in many + // places we expect things untyped and if we were to always return a + // (potentially typed) value, then we would have to reverse it in all + // those places. Still it may make sense to look into redesigning the + // whole thing one day. + // + // Currently the only way for the result to be NULL or have a type is if + // it is the result of a sole, unquoted variable expansion, function call, + // or context evaluation. + // + struct parse_names_result + { + bool not_null; + const value_type* type; + optional<const target_type*> pattern; + }; + + parse_names_result + parse_names (token&, token_type&, + names&, + pattern_mode, + bool chunk = false, + const char* what = "name", + const string* separators = &name_separators, + size_t pairn = 0, + const optional<string>& prj = nullopt, + const dir_path* dir = nullptr, + const string* type = nullptr, + bool cross = true); + + size_t + parse_names_trailer (token&, token_type&, + names&, + pattern_mode, + const char* what, + const string* separators, + size_t pairn, + const optional<string>& prj, + const dir_path* dir, + const string* type, + bool cross); + + size_t + expand_name_pattern (const location&, + names&&, + names&, + const char* what, + size_t pairn, + const dir_path* dir, + const string* type, + const target_type*); + + size_t + splice_names (const location&, + const names_view&, + names&&, + names&, + const char* what, + size_t pairn, + const optional<string>& prj, + const dir_path* dir, + const string* type); + + // Skip until newline or eos. + // + void + skip_line (token&, token_type&); + + // Skip until block-closing } or eos, taking into account nested blocks. + // + void + skip_block (token&, token_type&); + + // Return true if the name token can be considered a directive keyword. + // + bool + keyword (token&); + + // Buildspec. + // + buildspec + parse_buildspec_clause (token&, token_type&, size_t); + + // Customization hooks. + // + protected: + virtual lookup + lookup_variable (name&& qual, string&& name, const location&); + + // Utilities. + // + protected: + class enter_scope; + class enter_target; + + // Switch to a new current scope. Note that this function might also have + // to switch to a new root scope if the new current scope is in another + // project. So both must be saved and restored. + // + void + switch_scope (const dir_path&); + + void + process_default_target (token&); + + // Enter buildfile as a target. + // + void + enter_buildfile (const path&); + + // Lexer. + // + protected: + location + get_location (const token& t) const + { + return build2::get_location (t, *path_); + } + + token_type + next (token&, token_type&); + + // Be careful with peeking and switching the lexer mode. See keyword() + // for more information. + // + token_type + peek (); + + token_type + peek (lexer_mode m, char ps = '\0') + { + // The idea is that if we already have something peeked, then it should + // be in the same mode. We also don't re-set the mode since it may have + // expired after the first token. + // + if (peeked_) + { + assert (peek_.mode == m); + return peek_.token.type; + } + + mode (m, ps); + return peek (); + } + + const token& + peeked () const + { + assert (peeked_); + return peek_.token; + } + + void + mode (lexer_mode m, char ps = '\0') + { + if (replay_ != replay::play) + lexer_->mode (m, ps); + else + // As a sanity check, make sure the mode matches the next token. Note + // that we don't check the pair separator since it can be overriden by + // the lexer's mode() implementation. + // + assert (replay_i_ != replay_data_.size () && + replay_data_[replay_i_].mode == m); + } + + lexer_mode + mode () const + { + if (replay_ != replay::play) + return lexer_->mode (); + else + { + assert (replay_i_ != replay_data_.size ()); + return replay_data_[replay_i_].mode; + } + } + + void + expire_mode () + { + if (replay_ != replay::play) + lexer_->expire_mode (); + } + + // Token saving and replaying. Note that it can only be used in certain + // contexts. Specifically, the code that parses a replay must not interact + // with the lexer directly (e.g., the keyword() test). For now we don't + // enforce any of this. + // + // Note also that the peeked token is not part of the replay, until it + // is "got". + // + void + replay_save () + { + assert (replay_ == replay::stop); + replay_ = replay::save; + } + + void + replay_play () + { + assert ((replay_ == replay::save && !replay_data_.empty ()) || + (replay_ == replay::play && replay_i_ == replay_data_.size ())); + + if (replay_ == replay::save) + replay_path_ = path_; // Save old path. + + replay_i_ = 0; + replay_ = replay::play; + } + + void + replay_stop () + { + if (replay_ == replay::play) + path_ = replay_path_; // Restore old path. + + replay_data_.clear (); + replay_ = replay::stop; + } + + struct replay_guard + { + replay_guard (parser& p, bool start = true) + : p_ (start ? &p : nullptr) + { + if (p_ != nullptr) + p_->replay_save (); + } + + void + play () + { + if (p_ != nullptr) + p_->replay_play (); + } + + ~replay_guard () + { + if (p_ != nullptr) + p_->replay_stop (); + } + + private: + parser* p_; + }; + + // Stop saving and get the data. + // + replay_tokens + replay_data () + { + assert (replay_ == replay::save); + + replay_tokens r (move (replay_data_)); + replay_data_.clear (); + replay_ = replay::stop; + return r; + } + + // Set the data and start playing. + // + void + replay_data (replay_tokens&& d) + { + assert (replay_ == replay::stop); + + replay_path_ = path_; // Save old path. + + replay_data_ = move (d); + replay_i_ = 0; + replay_ = replay::play; + } + + // Implementation details, don't call directly. + // + replay_token + lexer_next () + { + lexer_mode m (lexer_->mode ()); // Get it first since it may expire. + return replay_token {lexer_->next (), path_, m}; + } + + const replay_token& + replay_next () + { + assert (replay_i_ != replay_data_.size ()); + const replay_token& rt (replay_data_[replay_i_++]); + + // Update the path. Note that theoretically it is possible that peeking + // at the next token will "change" the path of the current token. The + // workaround would be to call get_location() before peeking. + // + path_ = rt.file; + + return rt; + } + + // Diagnostics. + // + protected: + const fail_mark fail; + + protected: + bool pre_parse_ = false; + bool boot_; + + const path* path_; // Current path. + lexer* lexer_; + target* target_; // Current target, if any. + scope* scope_; // Current base scope (out_base). + scope* root_; // Current root scope (out_root). + + const dir_path* pbase_ = nullptr; // Current pattern base directory. + + std::stack<attributes> attributes_; + + target* default_target_; + names export_value_; + + replay_token peek_; + bool peeked_ = false; + + enum class replay {stop, save, play} replay_ = replay::stop; + replay_tokens replay_data_; + size_t replay_i_; // Position of the next token during replay. + const path* replay_path_; // Path before replay began (to be restored). + }; +} + +#endif // BUILD2_PARSER_HXX |