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diff --git a/tool/lrama/NEWS.md b/tool/lrama/NEWS.md new file mode 100644 index 0000000000..96aaaf94f5 --- /dev/null +++ b/tool/lrama/NEWS.md @@ -0,0 +1,382 @@ +# NEWS for Lrama + +## Lrama 0.6.5 (2024-03-25) + +### Typed Midrule Actions + +User can specify the type of mid rule action by tag (`<bar>`) instead of specifying it with in an action. + +``` +primary: k_case expr_value terms? + { + $<val>$ = p->case_labels; + p->case_labels = Qnil; + } + case_body + k_end + { + ... + } +``` + +can be written as + +``` +primary: k_case expr_value terms? + { + $$ = p->case_labels; + p->case_labels = Qnil; + }<val> + case_body + k_end + { + ... + } +``` + +`%destructor` for midrule action is invoked only when tag is specified by Typed Midrule Actions. + +Difference from Bison's Typed Midrule Actions is that tag is postposed in Lrama however it's preposed in Bison. + +Bison supports this feature from 3.1. + +## Lrama 0.6.4 (2024-03-22) + +### Parameterizing rules (preceded, terminated, delimited) + +Support `preceded`, `terminated` and `delimited` rules. + +``` +program: preceded(opening, X) + +// Expanded to + +program: preceded_opening_X +preceded_opening_X: opening X +``` + +``` +program: terminated(X, closing) + +// Expanded to + +program: terminated_X_closing +terminated_X_closing: X closing +``` + +``` +program: delimited(opening, X, closing) + +// Expanded to + +program: delimited_opening_X_closing +delimited_opening_X_closing: opening X closing +``` + +https://github.com/ruby/lrama/pull/382 + +### Support `%destructor` declaration + +User can set codes for freeing semantic value resources by using `%destructor`. +In general, these resources are freed by actions or after parsing. +However if syntax error happens in parsing, these codes may not be executed. +Codes associated to `%destructor` are executed when semantic value is popped from the stack by an error. + +``` +%token <val1> NUM +%type <val2> expr2 +%type <val3> expr + +%destructor { + printf("destructor for val1: %d\n", $$); +} <val1> // printer for TAG + +%destructor { + printf("destructor for val2: %d\n", $$); +} <val2> + +%destructor { + printf("destructor for expr: %d\n", $$); +} expr // printer for symbol +``` + +Bison supports this feature from 1.75b. + +https://github.com/ruby/lrama/pull/385 + +## Lrama 0.6.3 (2024-02-15) + +### Bring Your Own Stack + +Provide functionalities for Bring Your Own Stack. + +Ruby’s Ripper library requires their own semantic value stack to manage Ruby Objects returned by user defined callback method. Currently Ripper uses semantic value stack (`yyvsa`) which is used by parser to manage Node. This hack introduces some limitation on Ripper. For example, Ripper can not execute semantic analysis depending on Node structure. + +Lrama introduces two features to support another semantic value stack by parser generator users. + +1. Callback entry points + +User can emulate semantic value stack by these callbacks. +Lrama provides these five callbacks. Registered functions are called when each event happen. For example %after-shift function is called when shift happens on original semantic value stack. + +* `%after-shift` function_name +* `%before-reduce` function_name +* `%after-reduce` function_name +* `%after-shift-error-token` function_name +* `%after-pop-stack` function_name + +2. `$:n` variable to access index of each grammar symbols + +User also needs to access semantic value of their stack in grammar action. `$:n` provides the way to access to it. `$:n` is translated to the minus index from the top of the stack. +For example + +``` +primary: k_if expr_value then compstmt if_tail k_end + { + /*% ripper: if!($:2, $:4, $:5) %*/ + /* $:2 = -5, $:4 = -3, $:5 = -2. */ + } +``` + +https://github.com/ruby/lrama/pull/367 + +## Lrama 0.6.2 (2024-01-27) + +### %no-stdlib directive + +If `%no-stdlib` directive is set, Lrama doesn't load Lrama standard library for +parameterizing rules, stdlib.y. + +https://github.com/ruby/lrama/pull/344 + +## Lrama 0.6.1 (2024-01-13) + +### Nested parameterizing rules + +Allow to pass an instantiated rule to other parameterizing rules. + +``` +%rule constant(X) : X + ; + +%rule option(Y) : /* empty */ + | Y + ; + +%% + +program : option(constant(number)) // Nested rule + ; +%% +``` + +Allow to use nested parameterizing rules when define parameterizing rules. + +``` +%rule option(x) : /* empty */ + | X + ; + +%rule double(Y) : Y Y + ; + +%rule double_opt(A) : option(double(A)) // Nested rule + ; + +%% + +program : double_opt(number) + ; + +%% +``` + +https://github.com/ruby/lrama/pull/337 + +## Lrama 0.6.0 (2023-12-25) + +### User defined parameterizing rules + +Allow to define parameterizing rule by `%rule` directive. + +``` +%rule pair(X, Y): X Y { $$ = $1 + $2; } + ; + +%% + +program: stmt + ; + +stmt: pair(ODD, EVEN) <num> + | pair(EVEN, ODD) <num> + ; +``` + +https://github.com/ruby/lrama/pull/285 + +## Lrama 0.5.11 (2023-12-02) + +### Type specification of parameterizing rules + +Allow to specify type of rules by specifying tag, `<i>` in below example. +Tag is post-modification style. + +``` +%union { + int i; +} + +%% + +program : option(number) <i> + | number_alias? <i> + ; +``` + +https://github.com/ruby/lrama/pull/272 + + +## Lrama 0.5.10 (2023-11-18) + +### Parameterizing rules (option, nonempty_list, list) + +Support function call style parameterizing rules for `option`, `nonempty_list` and `list`. + +https://github.com/ruby/lrama/pull/197 + +### Parameterizing rules (separated_list) + +Support `separated_list` and `separated_nonempty_list` parameterizing rules. + +``` +program: separated_list(',', number) + +// Expanded to + +program: separated_list_number +separated_list_number: ε +separated_list_number: separated_nonempty_list_number +separated_nonempty_list_number: number +separated_nonempty_list_number: separated_nonempty_list_number ',' number +``` + +``` +program: separated_nonempty_list(',', number) + +// Expanded to + +program: separated_nonempty_list_number +separated_nonempty_list_number: number +separated_nonempty_list_number: separated_nonempty_list_number ',' number +``` + +https://github.com/ruby/lrama/pull/204 + +## Lrama 0.5.9 (2023-11-05) + +### Parameterizing rules (suffix) + +Parameterizing rules are template of rules. +It's very common pattern to write "list" grammar rule like: + +``` +opt_args: /* none */ + | args + ; + +args: arg + | args arg +``` + +Lrama supports these suffixes: + +* `?`: option +* `+`: nonempty list +* `*`: list + +Idea of Parameterizing rules comes from Menhir LR(1) parser generator (https://gallium.inria.fr/~fpottier/menhir/manual.html#sec32). + +https://github.com/ruby/lrama/pull/181 + +## Lrama 0.5.7 (2023-10-23) + +### Racc parser + +Replace Lrama's parser from hand written parser to LR parser generated by Racc. +Lrama uses `--embedded` option to generate LR parser because Racc is changed from default gem to bundled gem by Ruby 3.3 (https://github.com/ruby/lrama/pull/132). + +https://github.com/ruby/lrama/pull/62 + +## Lrama 0.5.4 (2023-08-17) + +### Runtime configuration for error recovery + +Meke error recovery function configurable on runtime by two new macros. + +* `YYMAXREPAIR`: Expected to return max length of repair operations. `%parse-param` is passed to this function. +* `YYERROR_RECOVERY_ENABLED`: Expected to return bool value to determine error recovery is enabled or not. `%parse-param` is passed to this function. + +https://github.com/ruby/lrama/pull/74 + +## Lrama 0.5.3 (2023-08-05) + +### Error Recovery + +Support token insert base Error Recovery. +`-e` option is needed to generate parser with error recovery functions. + +https://github.com/ruby/lrama/pull/44 + +## Lrama 0.5.2 (2023-06-14) + +### Named References + +Instead of positional references like `$1` or `$$`, +named references allow to access to symbol by name. + +``` +primary: k_class cpath superclass bodystmt k_end + { + $primary = new_class($cpath, $bodystmt, $superclass); + } +``` + +Alias name can be declared. + +``` +expr[result]: expr[ex-left] '+' expr[ex.right] + { + $result = $[ex-left] + $[ex.right]; + } +``` + +Bison supports this feature from 2.5. + +### Add parse params to some macros and functions + +`%parse-param` are added to these macros and functions to remove ytab.sed hack from Ruby. + +* `YY_LOCATION_PRINT` +* `YY_SYMBOL_PRINT` +* `yy_stack_print` +* `YY_STACK_PRINT` +* `YY_REDUCE_PRINT` +* `yysyntax_error` + +https://github.com/ruby/lrama/pull/40 + +See also: https://github.com/ruby/ruby/pull/7807 + +## Lrama 0.5.0 (2023-05-17) + +### stdin mode + +When `-` is given as grammar file name, reads the grammar source from STDIN, and takes the next argument as the input file name. This mode helps pre-process a grammar source. + +https://github.com/ruby/lrama/pull/8 + +## Lrama 0.4.0 (2023-05-13) + +This is the first version migrated to Ruby. +This version generates "parse.c" compatible with Bison 3.8.2. |