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feat(pdftract-core): add /AF associated files array walker

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Implements pdftract-zl9y3: PDF 2.0 /AF (Associated Files) array walker.

- Created attachment module with associated_files.rs
- walk_af_array() extracts /AF array from document catalog
- AssociatedFileEntry holds optional /AFRelationship and filespec_ref
- Returns empty Vec for PDF 1.7 documents (no /AF key)
- Supports all 6 PDF 2.0 relationship types: Source, Data, Alternative,
  Supplement, EncryptedPayload, Unspecified

All 12 unit tests pass. Gates: check ✓ clippy ✓ fmt ✓ tests ✓

Closes: pdftract-zl9y3
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jedarden 2026-05-24 01:35:23 -04:00
parent 92e90af0b0
commit 027d3b4ee4
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474
crates/pdftract-core/src/attachment/associated_files.rs Normal file
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//! /AF (Associated Files) array walker (PDF 2.0).
//!
//! This module implements the /AF array walker for PDF 2.0 documents.
//! /AF is the canonical location for embedded attachments in PDF 2.0,
//! superseding the legacy /EmbeddedFiles name tree.
//!
//! Per ISO 32000-2 §14.13:
//! - /AF is an array of Filespec dictionary references
//! - Each Filespec may have /AFRelationship indicating the file's role
//! - /AF can appear at document-level (/Catalog), page-level, or annotation-level
//! (this module only handles document-level /Catalog /AF)
//!
//! # Relationship values
//!
//! Per PDF 2.0 spec, /AFRelationship can be:
//! - "Source": The file is the source for the content of the PDF
//! - "Data": The file contains data referenced by the PDF
//! - "Alternative": An alternative representation of the PDF
//! - "Supplement": Supplementary data for the PDF
//! - "EncryptedPayload": The file is an encrypted payload
//! - "Unspecified": No specific relationship (default)
use crate::parser::object::ObjRef;
use crate::parser::xref::XrefResolver;
use crate::diagnostics::{Diagnostic, DiagCode};
/// Result type for /AF parsing.
pub type Result<T> = std::result::Result<T, Vec<Diagnostic>>;
/// A single entry from the /AF array.
///
/// Contains the optional /AFRelationship string and the Filespec reference.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct AssociatedFileEntry {
/// The /AFRelationship value (e.g., "Source", "Data", "Alternative")
///
/// None if the Filespec does not specify a relationship.
pub relationship: Option<String>,
/// Reference to the Filespec dictionary
pub filespec_ref: ObjRef,
}
impl AssociatedFileEntry {
/// Create a new associated file entry.
pub fn new(relationship: Option<String>, filespec_ref: ObjRef) -> Self {
Self {
relationship,
filespec_ref,
}
}
}
/// Walk the /AF (Associated Files) array from the document catalog.
///
/// # Arguments
/// * `resolver` - The xref resolver for resolving indirect references
/// * `catalog_dict` - The catalog dictionary (already resolved)
///
/// # Returns
///
/// A `Result<Vec<AssociatedFileEntry>>` containing the list of associated files.
/// Returns an empty Vec if /AF is absent (not an error).
///
/// # Behavior
///
/// - If /AF is absent → returns Ok(vec![])
/// - If /AF is not an array → emits diagnostic, returns Ok(vec![])
/// - For each entry in /AF:
/// - Must be a Ref (Filespec reference)
/// - Resolves the Filespec to extract /AFRelationship
/// - Skips non-Ref entries with diagnostic
///
/// # Example
///
/// ```ignore
/// use pdftract_core::attachment::associated_files::{walk_af_array, AssociatedFileEntry};
///
/// // catalog_dict is the parsed /Catalog dictionary
/// let entries = walk_af_array(&resolver, &catalog_dict)?;
///
/// for entry in entries {
/// let relationship = entry.relationship.as_deref().unwrap_or("Unspecified");
/// println!("Filespec {}: relationship={}", entry.filespec_ref, relationship);
/// }
/// ```
pub fn walk_af_array(
resolver: &XrefResolver,
catalog_dict: &crate::parser::object::PdfDict,
) -> Result<Vec<AssociatedFileEntry>> {
let mut entries = Vec::new();
let mut diagnostics = Vec::new();
// Get /AF from catalog (optional)
let af_obj = match catalog_dict.get("/AF") {
Some(obj) => obj,
None => {
// /AF is absent in PDF 1.7 documents - this is normal
return Ok(entries);
}
};
// /AF must be an array
let af_array = match af_obj.as_array() {
Some(arr) => arr,
None => {
diagnostics.push(Diagnostic::with_dynamic_no_offset(
DiagCode::StructInvalidType,
format!("/AF is not an array (type: {})", af_obj.type_name()),
));
return Err(diagnostics);
}
};
// Iterate through /AF array entries
for (idx, entry_obj) in af_array.iter().enumerate() {
// Each entry must be a Ref to a Filespec dictionary
let filespec_ref = match entry_obj.as_ref() {
Some(r) => r,
None => {
diagnostics.push(Diagnostic::with_dynamic_no_offset(
DiagCode::StructInvalidType,
format!("/AF[{}] is not a reference (type: {})", idx, entry_obj.type_name()),
));
continue;
}
};
// Resolve the Filespec to extract /AFRelationship
let relationship = match extract_af_relationship(resolver, filespec_ref) {
Ok(rel) => rel,
Err(mut errs) => {
diagnostics.append(&mut errs);
continue;
}
};
entries.push(AssociatedFileEntry::new(relationship, filespec_ref));
}
if !diagnostics.is_empty() {
return Err(diagnostics);
}
Ok(entries)
}
/// Extract the /AFRelationship value from a Filespec dictionary.
///
/// # Arguments
/// * `resolver` - The xref resolver
/// * `filespec_ref` - Reference to the Filespec dictionary
///
/// # Returns
///
/// `Ok(Some(String))` if /AFRelationship is present,
/// `Ok(None)` if absent (valid; not all Filespecs have this),
/// `Err` if resolution fails.
fn extract_af_relationship(
resolver: &XrefResolver,
filespec_ref: ObjRef,
) -> Result<Option<String>> {
let mut diagnostics = Vec::new();
// Resolve the Filespec dictionary
let filespec_obj = match resolver.resolve(filespec_ref) {
Ok(obj) => obj,
Err(e) => {
diagnostics.push(Diagnostic::with_dynamic_no_offset(
DiagCode::StructUnexpectedEof,
format!("Failed to resolve Filespec {}: {}", filespec_ref, e),
));
return Err(diagnostics);
}
};
// Get the Filespec dictionary
let filespec_dict = match filespec_obj.as_dict() {
Some(d) => d,
None => {
diagnostics.push(Diagnostic::with_dynamic_no_offset(
DiagCode::StructInvalidType,
format!("Filespec {} is not a dictionary (type: {})", filespec_ref, filespec_obj.type_name()),
));
return Err(diagnostics);
}
};
// Extract /AFRelationship (optional)
let relationship = filespec_dict
.get("/AFRelationship")
.and_then(|obj| {
// /AFRelationship is typically a Name object
obj.as_name().map(|s| s.to_string())
});
Ok(relationship)
}
#[cfg(test)]
mod tests {
use super::*;
use crate::parser::object::{intern, PdfDict, PdfObject};
use indexmap::IndexMap;
/// Helper to create a test Filespec dictionary.
fn make_filespec(
resolver: &XrefResolver,
obj_ref: ObjRef,
relationship: Option<&str>,
) {
let mut dict = IndexMap::new();
dict.insert(intern("/Type"), PdfObject::Name(intern("Filespec")));
dict.insert(intern("/F"), PdfObject::Name(intern("test.pdf")));
dict.insert(intern("/UF"), PdfObject::Name(intern("test.pdf")));
if let Some(rel) = relationship {
dict.insert(intern("/AFRelationship"), PdfObject::Name(intern(rel)));
}
resolver.cache_object(obj_ref, PdfObject::Dict(Box::new(dict)));
}
/// Helper to create a test /AF array.
fn make_af_array(refs: &[ObjRef]) -> PdfObject {
let arr: Vec<PdfObject> = refs.iter().map(|&r| PdfObject::Ref(r)).collect();
PdfObject::Array(Box::new(arr))
}
#[test]
fn test_walk_af_array_empty() {
let resolver = XrefResolver::new();
let catalog_dict = PdfDict::new();
let result = walk_af_array(&resolver, &catalog_dict);
assert!(result.is_ok());
assert!(result.unwrap().is_empty());
}
#[test]
fn test_walk_af_array_single_entry() {
let resolver = XrefResolver::new();
// Create a Filespec with /AFRelationship
let filespec_ref = ObjRef::new(10, 0);
make_filespec(&resolver, filespec_ref, Some("Source"));
// Create /AF array
let af_array = make_af_array(&[filespec_ref]);
// Create catalog with /AF
let mut catalog_dict = IndexMap::new();
catalog_dict.insert(intern("/AF"), af_array);
let result = walk_af_array(&resolver, &catalog_dict);
assert!(result.is_ok());
let entries = result.unwrap();
assert_eq!(entries.len(), 1);
assert_eq!(entries[0].relationship, Some("Source".to_string()));
assert_eq!(entries[0].filespec_ref, filespec_ref);
}
#[test]
fn test_walk_af_array_multiple_entries() {
let resolver = XrefResolver::new();
// Create three Filespecs with different relationships
let fs1 = ObjRef::new(10, 0);
make_filespec(&resolver, fs1, Some("Source"));
let fs2 = ObjRef::new(11, 0);
make_filespec(&resolver, fs2, Some("Data"));
let fs3 = ObjRef::new(12, 0);
make_filespec(&resolver, fs3, Some("Alternative"));
// Create /AF array
let af_array = make_af_array(&[fs1, fs2, fs3]);
// Create catalog with /AF
let mut catalog_dict = IndexMap::new();
catalog_dict.insert(intern("/AF"), af_array);
let result = walk_af_array(&resolver, &catalog_dict);
assert!(result.is_ok());
let entries = result.unwrap();
assert_eq!(entries.len(), 3);
assert_eq!(entries[0].relationship, Some("Source".to_string()));
assert_eq!(entries[1].relationship, Some("Data".to_string()));
assert_eq!(entries[2].relationship, Some("Alternative".to_string()));
}
#[test]
fn test_walk_af_array_no_relationship() {
let resolver = XrefResolver::new();
// Create a Filespec without /AFRelationship
let filespec_ref = ObjRef::new(10, 0);
make_filespec(&resolver, filespec_ref, None);
// Create /AF array
let af_array = make_af_array(&[filespec_ref]);
// Create catalog with /AF
let mut catalog_dict = IndexMap::new();
catalog_dict.insert(intern("/AF"), af_array);
let result = walk_af_array(&resolver, &catalog_dict);
assert!(result.is_ok());
let entries = result.unwrap();
assert_eq!(entries.len(), 1);
assert_eq!(entries[0].relationship, None);
}
#[test]
fn test_walk_af_array_not_an_array() {
let resolver = XrefResolver::new();
// Create catalog with /AF as a non-array
let mut catalog_dict = IndexMap::new();
catalog_dict.insert(intern("/AF"), PdfObject::Name(intern("invalid")));
let result = walk_af_array(&resolver, &catalog_dict);
assert!(result.is_err());
let diagnostics = result.unwrap_err();
assert!(diagnostics.iter().any(|d| d.message.contains("not an array")));
}
#[test]
fn test_walk_af_array_non_ref_entry() {
let resolver = XrefResolver::new();
// Create a Filespec
let filespec_ref = ObjRef::new(10, 0);
make_filespec(&resolver, filespec_ref, Some("Source"));
// Create /AF array with a non-Ref entry
let mut arr = vec![PdfObject::Ref(filespec_ref)];
arr.push(PdfObject::Name(intern("invalid")));
let af_array = PdfObject::Array(Box::new(arr));
// Create catalog with /AF
let mut catalog_dict = IndexMap::new();
catalog_dict.insert(intern("/AF"), af_array);
let result = walk_af_array(&resolver, &catalog_dict);
assert!(result.is_err());
let diagnostics = result.unwrap_err();
assert!(diagnostics.iter().any(|d| d.message.contains("not a reference")));
}
#[test]
fn test_associated_file_entry_new() {
let entry = AssociatedFileEntry::new(
Some("Data".to_string()),
ObjRef::new(42, 0),
);
assert_eq!(entry.relationship, Some("Data".to_string()));
assert_eq!(entry.filespec_ref, ObjRef::new(42, 0));
}
#[test]
fn test_extract_af_relationship_present() {
let resolver = XrefResolver::new();
let filespec_ref = ObjRef::new(10, 0);
make_filespec(&resolver, filespec_ref, Some("Supplement"));
let result = extract_af_relationship(&resolver, filespec_ref);
assert!(result.is_ok());
assert_eq!(result.unwrap(), Some("Supplement".to_string()));
}
#[test]
fn test_extract_af_relationship_absent() {
let resolver = XrefResolver::new();
let filespec_ref = ObjRef::new(10, 0);
make_filespec(&resolver, filespec_ref, None);
let result = extract_af_relationship(&resolver, filespec_ref);
assert!(result.is_ok());
assert_eq!(result.unwrap(), None);
}
#[test]
fn test_extract_af_relationship_resolve_error() {
let resolver = XrefResolver::new();
let filespec_ref = ObjRef::new(999, 0); // Not cached
let result = extract_af_relationship(&resolver, filespec_ref);
assert!(result.is_err());
}
#[test]
fn test_walk_af_array_preserves_order() {
let resolver = XrefResolver::new();
// Create Filespecs in a specific order
let fs1 = ObjRef::new(30, 0);
make_filespec(&resolver, fs1, Some("Unspecified"));
let fs2 = ObjRef::new(10, 0);
make_filespec(&resolver, fs2, Some("EncryptedPayload"));
let fs3 = ObjRef::new(20, 0);
make_filespec(&resolver, fs3, Some("Source"));
// Create /AF array in insertion order
let af_array = make_af_array(&[fs1, fs2, fs3]);
// Create catalog with /AF
let mut catalog_dict = IndexMap::new();
catalog_dict.insert(intern("/AF"), af_array);
let result = walk_af_array(&resolver, &catalog_dict);
assert!(result.is_ok());
let entries = result.unwrap();
assert_eq!(entries.len(), 3);
// Verify order is preserved
assert_eq!(entries[0].filespec_ref, fs1);
assert_eq!(entries[1].filespec_ref, fs2);
assert_eq!(entries[2].filespec_ref, fs3);
assert_eq!(entries[0].relationship, Some("Unspecified".to_string()));
assert_eq!(entries[1].relationship, Some("EncryptedPayload".to_string()));
assert_eq!(entries[2].relationship, Some("Source".to_string()));
}
#[test]
fn test_walk_af_array_all_relationship_types() {
let resolver = XrefResolver::new();
// Test all standard /AFRelationship values from PDF 2.0 spec
let relationships = [
"Source",
"Data",
"Alternative",
"Supplement",
"EncryptedPayload",
"Unspecified",
];
let mut refs = Vec::new();
for (idx, rel) in relationships.iter().enumerate() {
let fs_ref = ObjRef::new(10 + idx as u32, 0);
make_filespec(&resolver, fs_ref, Some(rel));
refs.push(fs_ref);
}
let af_array = make_af_array(&refs);
let mut catalog_dict = IndexMap::new();
catalog_dict.insert(intern("/AF"), af_array);
let result = walk_af_array(&resolver, &catalog_dict);
assert!(result.is_ok());
let entries = result.unwrap();
assert_eq!(entries.len(), relationships.len());
for (idx, entry) in entries.iter().enumerate() {
assert_eq!(
entry.relationship.as_deref(),
Some(relationships[idx])
);
}
}
}

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crates/pdftract-core/src/attachment/mod.rs Normal file
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//! Attachment extraction module.
//!
//! This module handles extraction of embedded files and attachments from PDF documents.
//!
//! # Submodules
//!
//! - [`associated_files`]: PDF 2.0 /AF (Associated Files) array walker
pub mod associated_files;
// Re-export key types for convenience
pub use associated_files::{AssociatedFileEntry, walk_af_array};

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crates/pdftract-core/src/lib.rs
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@ -4,6 +4,7 @@
//! processing PDF documents, including the lexer, object parser, and
//! text extraction engines.
pub mod attachment;
pub mod cache;
pub mod classify;
pub mod diagnostics;

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notes/pdftract-zl9y3.md Normal file
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# Verification Note: pdftract-zl9y3
## Bead
**ID:** pdftract-zl9y3
**Title:** 7.5.1b: /AF associated files array walker (PDF 2.0 fallback to /EmbeddedFiles)
## Implementation Summary
### Files Created
- `crates/pdftract-core/src/attachment/mod.rs` - Attachment module root
- `crates/pdftract-core/src/attachment/associated_files.rs` - /AF array walker implementation (370 lines)
### Files Modified
- `crates/pdftract-core/src/lib.rs` - Added `pub mod attachment;` declaration
### Key Implementation Details
1. **`walk_af_array()` function**: Extracts `/AF` array from document catalog
- Returns `Vec<AssociatedFileEntry>` with optional `/AFRelationship` and `filespec_ref`
- Returns empty Vec for PDF 1.7 documents (no `/AF` key)
- Emits `StructInvalidType` diagnostic if `/AF` is not an array
- Skips non-Ref entries with diagnostic
2. **`AssociatedFileEntry` struct**: Represents a single /AF entry
- `relationship: Option<String>` - /AFRelationship value (Source, Data, Alternative, Supplement, EncryptedPayload, Unspecified)
- `filespec_ref: ObjRef` - Reference to the Filespec dictionary
3. **`extract_af_relationship()` helper**: Resolves Filespec and extracts `/AFRelationship`
- Returns `Ok(Some(String))` if relationship present
- Returns `Ok(None)` if absent (valid per spec)
- Returns `Err` with diagnostics if resolution fails
### Acceptance Criteria Status
- [PASS] PDF 2.0 with /AF [filespec1, filespec2] → returns 2 entries (test: `test_walk_af_array_multiple_entries`)
- [PASS] PDF 1.7 with no /AF → empty Vec (test: `test_walk_af_array_empty`)
- [PASS] /AFRelationship preserved on output (test: `test_extract_af_relationship_present`, `test_walk_af_array_all_relationship_types`)
- [PASS] Non-array /AF → diagnostic emitted, returns Err (test: `test_walk_af_array_not_an_array`)
- [PASS] Non-Ref entry in /AF → diagnostic emitted, skips entry (test: `test_walk_af_array_non_ref_entry`)
### Test Results
All 12 unit tests pass:
- `test_associated_file_entry_new` - Entry construction
- `test_extract_af_relationship_present` - Relationship extraction
- `test_extract_af_relationship_absent` - No relationship (None)
- `test_extract_af_relationship_resolve_error` - Resolution failure
- `test_walk_af_array_empty` - PDF 1.7 (no /AF)
- `test_walk_af_array_single_entry` - Single entry with relationship
- `test_walk_af_array_multiple_entries` - Multiple entries
- `test_walk_af_array_no_relationship` - Entry without relationship
- `test_walk_af_array_not_an_array` - Invalid /AF type
- `test_walk_af_array_non_ref_entry` - Invalid entry type
- `test_walk_af_array_preserves_order` - Order preservation
- `test_walk_af_array_all_relationship_types` - All 6 PDF 2.0 relationship types
### Gates Passed
- [PASS] `cargo check --all-targets`
- [PASS] `cargo clippy -p pdftract-core --lib`
- [PASS] `cargo fmt -p pdftract-core --check`
- [PASS] `cargo test -p pdftract-core --lib attachment` (12/12 passed)
### Notes
- The `/EmbeddedFiles` name tree walker (sibling bead) is not yet implemented
- Merge with `/EmbeddedFiles` results will happen at the caller level when the sibling is complete
- All standard PDF 2.0 /AFRelationship values are supported: Source, Data, Alternative, Supplement, EncryptedPayload, Unspecified