pdftract/notes/bf-66dwv.md

bf-66dwv: Implement parsing for unmapped_glyph_names from config files

Summary

Implemented parsing logic for the unmapped_glyph_names field from config files using the UnmappedGlyphNamesConfig struct that was added in bf-3vo80.

Changes Made

File: crates/pdftract-core/build.rs

Lines 1036-1067: Updated generate_unmapped_glyph_names() function to use proper deserialization

Before:

let data: serde_json::Value = serde_json::from_str(&json_content)
    .unwrap_or_else(|_| panic!("Failed to parse {}", actual_unmapped_path.display()));

// Extract the unmapped_glyph_names array
let names_array = data
    .get("unmapped_glyph_names")
    .and_then(|v| v.as_array())
    .expect("unmapped_glyph_names array missing");

After:

// Parse using UnmappedGlyphNamesConfig struct for proper deserialization
let config: UnmappedGlyphNamesConfig = serde_json::from_str(&json_content)
    .unwrap_or_else(|e| panic!("Failed to parse {}: {}", actual_unmapped_path.display(), e));

// Extract the unmapped_glyph_names array from the config
let names_array = &config.unmapped_glyph_names;

Acceptance Criteria Verification

✅ PASS: unmapped_glyph_names can be parsed from config files

• The UnmappedGlyphNamesConfig struct deserializes the JSON config correctly
• Build script successfully reads build/unmapped-glyph-names.json and extracts the unmapped_glyph_names array

✅ PASS: Parser handles both empty lists and populated lists

• Empty lists work: Vec<String> is empty, generates no HashSet insertions
• Populated lists work: Current config has 12 entries, all parsed correctly

✅ PASS: Integration with existing deserialization logic works

• No changes required to the rest of the build script
• Generated unmapped_glyph_names.rs file output is identical to before (just using proper deserialization now)

✅ PASS: Code compiles without errors

• cargo build -p pdftract-core succeeds cleanly
• No warnings or errors

Test Verification

Verified by inspecting the generated file at target/debug/build/pdftract-core-*/out/unmapped_glyph_names.rs:

/// Glyph count: 12
pub static UNMAPPED_GLYPH_NAMES: LazyLock<HashSet<&'static str>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    set.insert(".notdef");
    set.insert(".null");
    set.insert("g000");
    set.insert("g001");
    set.insert("g002");
    set.insert("g003");
    set.insert("g004");
    set.insert("g005");
    set.insert("g006");
    set.insert("g007");
    set.insert("g008");
    set.insert("g009");
    set
});

All 12 glyph names from build/unmapped-glyph-names.json are correctly parsed and inserted into the HashSet.

Config File Format

The current config format (JSON) is:

{
  "unmapped_glyph_names": [".notdef", ".null", "g000", ...],
  "description": "Glyph names that should be skipped...",
  "version": "1.0"
}

The UnmappedGlyphNamesConfig struct supports:

• Required field: unmapped_glyph_names: Vec<String>
• Optional fields: description: Option<String>, version: Option<String>

The struct definition uses #[serde(default)] for optional fields, making them truly optional during parsing.

Implementation Notes

1. Type Safety: Changed from serde_json::Value (dynamic) to UnmappedGlyphNamesConfig (static typing), providing better compile-time guarantees and clearer error messages

2. Better Error Messages: The new panic message includes the actual deserialization error, making debugging easier if the config file is malformed

3. No Functional Changes: The output is identical to the previous implementation; this is purely a refactoring to use the proper deserialization structure