You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: doc_decoder.rs
    path of file: ./repos/ritual/qt_ritual/src
    
    the code of the file until where you have to start completion: //! Converts Qt docs from the internal format.

use log::{info, trace};
use ritual_common::errors::{bail, err_msg, Result, ResultExt};
use select::document::Document;
use std::io::Read;
use std::path::Path;

/// Decoded documentation data.
#[derive(Debug)]
pub struct DocData {
    index: Vec<DocIndexItem>,
    connection: rusqlite::Connection,
}

/// An item of the documentation's index.
#[derive(Debug, Clone)]
pub struct DocIndexItem {
    /// Identifier in the index.
    /// For types and methods, this is roughly the same as
    /// the fully qualified name but has some quirks.
    pub name: String,
    /// Identifier of the virtual HTML file this item refers to.
    pub document_id: i32,
    /// HTML link anchor in the file this item refers to,
    /// or `None` if the item refers to the entire file (e.g. if it's a class).
    pub anchor: Option<String>,
    /// If `true`, this item was previously accessed using `DocData::find_index_item`.
    pub accessed: bool,
}

impl DocData {
    /// Returns all index items.
    pub fn index(&self) -> &[DocIndexItem] {
        &self.index
    }

    /// Returns parsed HTML document by id.
    pub fn document(&self, id: i32) -> Result<Document> {
        let file_data_query = "sele
    
    pub fn new(qt_crate_name: &str, docs_path: &Path) -> Result<Self> {
        if !docs_path.exists() {
            bail!(
                "Documentation directory does not exist: {}",
                docs_path.display()
            );
        }
        let doc_file_name = if qt_crate_name.starts_with("qt_3d_") {
            "qt3d".to_string()
        } else {
            qt_crate_name.replace("_", "")
        };

        let doc_file_path = docs_path.join(format!("{}.qch", doc_file_name));
        if !doc_file_path.exists() {
            bail!(
                "Documentation file does not exist: {}",
                doc_file_path.display()
            );
        }
        info!("Adding Qt documentation from {}", doc_file_path.display());
        let connection = rusqlite::Connection::open_with_flags(
            &doc_file_path,
            rusqlite::OpenFlags::SQLITE_OPEN_READ_ONLY,
        )?;

        let mut index_data = Vec::new();
        {
            let index_query = "select IndexTable.Identifier, IndexTable.FileId, IndexTable.Anchor \
                               from IndexTable";
            let mut index = connection.prepare(index_query)?;
            let mut index_rows = index.query(rusqlite::NO_PARAMS)?;
            while let Some(index_row) = index_rows.next() {
                let index_row = index_row?;
                let name: String = index_row.get_checked(0)?;
                let file_id: i32 = index_row.get_checked(1)?;
                let anchor: Option<String> = index_row.get_checked(2)?;
                index_data.push(DocIndexItem {
                    name,
                    document_id: file_id,
                    anchor,
                    accessed: false,
                });
            }
        }
        trace!("doc index: {:?}", index_data);
        Ok(DocData {
            index: index_data,
            connection,
        })
    }