Needs to create actual structs, not just a tree

[ctrlcctrlv]

Right now this is just a mostly complete grammar which generates an abstract syntax tree (AST).

The default test, test_feaparser on src/lib.rs, takes this input:

@lol = [Qol Mol @lol];
languagesystem DFLT dflt;
language DEU required;
include(te\)st);
# include(te)st); would fail
include (lol);

anonymous jig { @lol = [lol]; {@Q = [Q R S T];} name ";}{"; {}; "}"; } jig;
anonymous jjig { } jjig;
anonymous jjig {} jjig;
anonymous FIVE { {} {} {} } FIVE;
# This'd be invalid FEA syntax due to tag mismatch. It's up to struct builder to check this! Not possible in a grammar.
anonymous LAST {
    It's the end of the world as we know it
    And I feel fine!
} FRST;

anonymous LAST {} LAST;

name 0x3 0x1 0x411;

feature mark {

} mark;

feature liga {
    featureNames {
        name 0x3 0x1 0x411 "Feature description for MS Platform, script Unicode, language Japanese";
        name "b";
    };
    name "C";
} liga;

table GDEF {
    LigatureCaretByPos lol 0;
} GDEF;

table head {
    FontRevision 0.0;
} head;

table OS/2 {
    FSType 4;
    Panose 2 15 0 0 2 2 8 2 9 4;
    TypoAscender 800;
    TypoDescender -200; # Note that TypoDescender is negative for descent below the baseline.
    winAscent 832;
    winDescent 321; # Note that winDescent is positive for descent below the baseline.
    UnicodeRange
        0   # Basic Latin
        1   # Latin-1 Supplement
        9   # Cyrillic
        55  # CJK Compatibility
        59  # CJK Unified Ideographs
        60  # Private Use Area
        ;
    CodePageRange
        1252    # Latin 1
        1251    # Cyrillic
        932     # JIS/Japan
        ;
    XHeight 400;
    CapHeight 600;
    WeightClass 800;
    WidthClass 3;
    Vendor "ADBE";
    FamilyClass 0x0805;  # Class 8 (Sans-serif), Subclass 5 (Neo-grotesque Gothic)
} OS/2;

feature aalt {
    featureNames {
        name "Fancy Q's";
    };
    lookup aalt_1 {
        sub Q from [Q.ss01 Q.ss02 Q.ss03];
    } aalt_1;
} aalt;


variation rvrn heavy {
    lookup symbols_heavy;
    lookup letters_heavy;
} rvrn;

anchorDef 120 120 ANCHOR_1;
anchorDef 120 -20 contourpoint 5 ANCHOR_2;
valueRecordDef -10 FIRST_KERN;
valueRecordDef <0 0 20 0> SECOND_KERN;

feature liga {
    sub A by B;
    sub @A by @B;
    sub B by A B C;
    sub f f by f_f;
    subtable;
    sub f i by f_i;
    sub f l by f_l;
    sub f l' lookup test;
    sub f l' by y;
    sub Q by NULL;
    lookup inside_lu {sub \NULL by NULL;}inside_lu;
} liga;
# comment ça va
#

And makes this enormous tree:

 ├─ class_definition_statement
 │  ├─ class_inner "lol"
 │  └─ inline_class
 │     ├─ barename "Qol"
 │     ├─ barename "Mol"
 │     └─ class_inner "lol"
 ├─ languagesystem_statement
 │  ├─ script
 │  │  └─ tag "DFLT"
 │  └─ language
 │     └─ tag "dflt"
 ├─ language_statement
 │  ├─ language
 │  │  └─ tag "DEU"
 │  └─ required_tag "required"
 ├─ include_statement
 │  └─ include_inner "te\\)st"
 ├─ COMMENT
 │  └─ comment_inner "include(te)st);\ would\ fail"
 ├─ include_statement
 │  └─ include_inner "lol"
 ├─ anonymous_statement
 │  ├─ tag "jig"
 │  ├─ anonymous_inner "@lol\ =\ [lol];"
 │  ├─ anonymous_inner "{@Q\ =\ [Q\ R\ S\ T];}"
 │  ├─ anonymous_inner "name"
 │  ├─ anonymous_inner "";}{";"
 │  ├─ anonymous_inner "{};"
 │  ├─ anonymous_inner ""}";"
 │  └─ tag "jig"
 ├─ anonymous_statement
 │  ├─ tag "jjig"
 │  └─ tag "jjig"
 ├─ anonymous_statement
 │  ├─ tag "jjig"
 │  └─ tag "jjig"
 ├─ anonymous_statement
 │  ├─ tag "FIVE"
 │  ├─ anonymous_inner "{}"
 │  ├─ anonymous_inner "{}"
 │  ├─ anonymous_inner "{}"
 │  └─ tag "FIVE"
 ├─ COMMENT
 │  └─ comment_inner "This'd\ be\ invalid\ FEA\ syntax\ due\ to\ tag\ mismatch.\ It's\ up\ to\ struct\ builder\ to\ check\ this!\ Not\ possible\ in\ a\ grammar."
 ├─ anonymous_statement
 │  ├─ tag "LAST"
 │  ├─ anonymous_inner "It's\ the\ end\ of\ the\ world\ as\ we\ know\ it\n\ \ \ \ \ \ \ \ And\ I\ feel\ fine!"
 │  └─ tag "FRST"
 ├─ name_statement
 │  ├─ fea_integer "0x3"
 │  ├─ fea_integer "0x1"
 │  └─ fea_integer "0x411"
 ├─ feature_statement
 │  ├─ tag "mark"
 │  └─ tag "mark"
 ├─ feature_statement
 │  ├─ tag "liga"
 │  ├─ feature_names_statement
 │  │  ├─ name_statement
 │  │  │  ├─ fea_integer "0x3"
 │  │  │  ├─ fea_integer "0x1"
 │  │  │  ├─ fea_integer "0x411"
 │  │  │  └─ quoted_string
 │  │  │     └─ qs_inner "Feature\ description\ for\ MS\ Platform,\ script\ Unicode,\ language\ Japanese"
 │  │  └─ name_statement
 │  │     └─ quoted_string
 │  │        └─ qs_inner "b"
 │  ├─ name_statement
 │  │  └─ quoted_string
 │  │     └─ qs_inner "C"
 │  └─ tag "liga"
 ├─ table_statement
 │  └─ table_gdef_statement
 │     └─ gdef_block
 │        └─ gdef_statement
 │           └─ ligaturecaretbypos_gdef_statement
 │              ├─ barename "lol"
 │              └─ fea_integer "0"
 ├─ table_statement
 │  └─ table_head_statement
 │     └─ font_revision_statement
 │        └─ version "0.0"
 ├─ table_statement
 │  └─ table_os2_statement
 │     └─ os2_block
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "FSType"
 │        │     └─ fea_integer "4"
 │        ├─ os2_statement
 │        │  └─ os2_panose
 │        │     ├─ fea_integer "2"
 │        │     ├─ fea_integer "15"
 │        │     ├─ fea_integer "0"
 │        │     ├─ fea_integer "0"
 │        │     ├─ fea_integer "2"
 │        │     ├─ fea_integer "2"
 │        │     ├─ fea_integer "8"
 │        │     ├─ fea_integer "2"
 │        │     ├─ fea_integer "9"
 │        │     └─ fea_integer "4"
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "TypoAscender"
 │        │     └─ fea_integer "800"
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "TypoDescender"
 │        │     └─ fea_integer "-200"
 │        ├─ COMMENT
 │        │  └─ comment_inner "Note\ that\ TypoDescender\ is\ negative\ for\ descent\ below\ the\ baseline."
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "winAscent"
 │        │     └─ fea_integer "832"
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "winDescent"
 │        │     └─ fea_integer "321"
 │        ├─ COMMENT
 │        │  └─ comment_inner "Note\ that\ winDescent\ is\ positive\ for\ descent\ below\ the\ baseline."
 │        ├─ os2_statement
 │        │  ├─ os2_range
 │        │  │  ├─ os2_range_tag "UnicodeRange"
 │        │  │  ├─ fea_integer "0"
 │        │  │  ├─ COMMENT
 │        │  │  │  └─ comment_inner "Basic\ Latin"
 │        │  │  ├─ fea_integer "1"
 │        │  │  ├─ COMMENT
 │        │  │  │  └─ comment_inner "Latin-1\ Supplement"
 │        │  │  ├─ fea_integer "9"
 │        │  │  ├─ COMMENT
 │        │  │  │  └─ comment_inner "Cyrillic"
 │        │  │  ├─ fea_integer "55"
 │        │  │  ├─ COMMENT
 │        │  │  │  └─ comment_inner "CJK\ Compatibility"
 │        │  │  ├─ fea_integer "59"
 │        │  │  ├─ COMMENT
 │        │  │  │  └─ comment_inner "CJK\ Unified\ Ideographs"
 │        │  │  └─ fea_integer "60"
 │        │  └─ COMMENT
 │        │     └─ comment_inner "Private\ Use\ Area"
 │        ├─ os2_statement
 │        │  ├─ os2_range
 │        │  │  ├─ os2_range_tag "CodePageRange"
 │        │  │  ├─ fea_integer "1252"
 │        │  │  ├─ COMMENT
 │        │  │  │  └─ comment_inner "Latin\ 1"
 │        │  │  ├─ fea_integer "1251"
 │        │  │  ├─ COMMENT
 │        │  │  │  └─ comment_inner "Cyrillic"
 │        │  │  └─ fea_integer "932"
 │        │  └─ COMMENT
 │        │     └─ comment_inner "JIS/Japan"
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "XHeight"
 │        │     └─ fea_integer "400"
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "CapHeight"
 │        │     └─ fea_integer "600"
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "WeightClass"
 │        │     └─ fea_integer "800"
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "WidthClass"
 │        │     └─ fea_integer "3"
 │        ├─ os2_statement
 │        │  └─ os2_vendor
 │        │     └─ os2_vendor_id "ADBE"
 │        ├─ os2_statement
 │        │  └─ os2_single_number
 │        │     ├─ os2_single_number_tag "FamilyClass"
 │        │     └─ fea_integer "0x0805"
 │        └─ COMMENT
 │           └─ comment_inner "Class\ 8\ (Sans-serif),\ Subclass\ 5\ (Neo-grotesque\ Gothic)"
 ├─ feature_statement
 │  ├─ tag "aalt"
 │  ├─ feature_names_statement
 │  │  └─ name_statement
 │  │     └─ quoted_string
 │  │        └─ qs_inner "Fancy\ Q's"
 │  ├─ lookup_statement
 │  │  ├─ lookup_tag "lookup"
 │  │  ├─ lookup_name "aalt_1"
 │  │  ├─ gsub_statement
 │  │  │  └─ gsub_3
 │  │  │     ├─ sub_tag "sub"
 │  │  │     ├─ barename "Q"
 │  │  │     ├─ from_tag "from"
 │  │  │     └─ inline_class
 │  │  │        ├─ barename "Q.ss01"
 │  │  │        ├─ barename "Q.ss02"
 │  │  │        └─ barename "Q.ss03"
 │  │  └─ lookup_name "aalt_1"
 │  └─ tag "aalt"
 ├─ variation_statement
 │  ├─ variation_tag "variation"
 │  ├─ tag "rvrn"
 │  ├─ variation_name "heavy"
 │  ├─ variation_block
 │  │  ├─ variation_lookup_statement
 │  │  │  ├─ lookup_tag "lookup"
 │  │  │  └─ lookup_name "symbols_heavy"
 │  │  └─ variation_lookup_statement
 │  │     ├─ lookup_tag "lookup"
 │  │     └─ lookup_name "letters_heavy"
 │  └─ tag "rvrn"
 ├─ anchordef_statement
 │  ├─ anchordef_tag "anchorDef"
 │  ├─ anchor_coordinates
 │  │  ├─ fea_integer "120"
 │  │  └─ fea_integer "120"
 │  └─ anchor_name
 │     └─ name_inner "ANCHOR_1"
 ├─ anchordef_statement
 │  ├─ anchordef_tag "anchorDef"
 │  ├─ anchor_coordinates
 │  │  ├─ fea_integer "120"
 │  │  └─ fea_integer "-20"
 │  ├─ contourpoint
 │  │  ├─ contourpoint_tag "contourpoint"
 │  │  └─ fea_integer "5"
 │  └─ anchor_name
 │     └─ name_inner "ANCHOR_2"
 ├─ valuerecorddef_statement
 │  ├─ valuerecorddef_tag "valueRecordDef"
 │  ├─ valuerecord
 │  │  └─ valuerecord1
 │  │     └─ fea_integer "-10"
 │  └─ valuerecord_name
 │     └─ name_inner "FIRST_KERN"
 ├─ valuerecorddef_statement
 │  ├─ valuerecorddef_tag "valueRecordDef"
 │  ├─ valuerecord
 │  │  └─ valuerecord4
 │  │     ├─ fea_integer "0"
 │  │     ├─ fea_integer "0"
 │  │     ├─ fea_integer "20"
 │  │     └─ fea_integer "0"
 │  └─ valuerecord_name
 │     └─ name_inner "SECOND_KERN"
 ├─ feature_statement
 │  ├─ tag "liga"
 │  ├─ gsub_statement
 │  │  └─ gsub_1a
 │  │     ├─ sub_tag "sub"
 │  │     ├─ barename "A"
 │  │     ├─ by_tag "by"
 │  │     └─ barename "B"
 │  ├─ gsub_statement
 │  │  └─ gsub_6
 │  │     ├─ sub_tag "sub"
 │  │     ├─ class_inner "A"
 │  │     ├─ by_tag "by"
 │  │     └─ class_inner "B"
 │  ├─ gsub_statement
 │  │  └─ gsub_2a
 │  │     ├─ sub_tag "sub"
 │  │     ├─ barename "B"
 │  │     ├─ by_tag "by"
 │  │     └─ gsub_glyph_seq
 │  │        ├─ barename "A"
 │  │        ├─ barename "B"
 │  │        └─ barename "C"
 │  ├─ gsub_statement
 │  │  └─ gsub_4
 │  │     ├─ sub_tag "sub"
 │  │     ├─ gsub_glyph_seq
 │  │     │  ├─ barename "f"
 │  │     │  └─ barename "f"
 │  │     ├─ by_tag "by"
 │  │     └─ barename "f_f"
 │  ├─ subtable_statement "subtable"
 │  ├─ gsub_statement
 │  │  └─ gsub_4
 │  │     ├─ sub_tag "sub"
 │  │     ├─ gsub_glyph_seq
 │  │     │  ├─ barename "f"
 │  │     │  └─ barename "i"
 │  │     ├─ by_tag "by"
 │  │     └─ barename "f_i"
 │  ├─ gsub_statement
 │  │  └─ gsub_4
 │  │     ├─ sub_tag "sub"
 │  │     ├─ gsub_glyph_seq
 │  │     │  ├─ barename "f"
 │  │     │  └─ barename "l"
 │  │     ├─ by_tag "by"
 │  │     └─ barename "f_l"
 │  ├─ gsub_statement
 │  │  └─ gsub_6
 │  │     ├─ sub_tag "sub"
 │  │     ├─ barename "f"
 │  │     ├─ barename "l"
 │  │     └─ apply_lookup
 │  │        ├─ lookup_tag "lookup"
 │  │        └─ lookup_name "test"
 │  ├─ gsub_statement
 │  │  └─ gsub_6
 │  │     ├─ sub_tag "sub"
 │  │     ├─ barename "f"
 │  │     ├─ barename "l"
 │  │     ├─ apply_by "'"
 │  │     ├─ by_tag "by"
 │  │     └─ barename "y"
 │  ├─ gsub_statement
 │  │  └─ gsub_2b
 │  │     ├─ sub_tag "sub"
 │  │     ├─ barename "Q"
 │  │     ├─ by_tag "by"
 │  │     └─ null_token "NULL"
 │  ├─ lookup_statement
 │  │  ├─ lookup_tag "lookup"
 │  │  ├─ lookup_name "inside_lu"
 │  │  ├─ gsub_statement
 │  │  │  └─ gsub_2b
 │  │  │     ├─ sub_tag "sub"
 │  │  │     ├─ barename "\\NULL"
 │  │  │     ├─ by_tag "by"
 │  │  │     └─ null_token "NULL"
 │  │  └─ lookup_name "inside_lu"
 │  └─ tag "liga"
 ├─ COMMENT
 │  └─ comment_inner "comment\ ça\ va"
 └─ COMMENT "#"

Sorry to make you scroll that much.

The grammar is, as you can see, very far along. But not much else is. @simoncozens knew I was working on this, and was unhappy with wrl/otf-fea-rs. As am I—various issues there, especially wrl/otf-fea-rs#4, show that it's unsuitable for even basic inputs.

So, I uploaded this for him to work on as I'm busy w/other stuff…but I'm still very interested in this problem so am making him issues to close. Basically this is the major one: we need to be generating structs.

The following checks need to be run, which are not run by the parser:

• Whether tags match. I can't specify in a grammar that the beginning tag and end tag must equal one another.
• Whether classes exist before being called. Goes also for anchors.
• Whether lookups exist before being called.

Pinging also @davelab6, who may be interested to know that this project is now public, and likely to replace wrl/otf-fea-rs.