a2kit 4.4.1

//! # `a2kit` main library
//! 
//! This library manipulates retro language files and disk images, with emphasis on Apple II.
//! 
//! ## Language Services
//! 
//! Language modules are designed to be complementary to the needs of language servers that
//! use the language server protocol (LSP).
//! Specific language services are in modules named after the language, at present:
//! * `lang::applesoft` handles Applesoft BASIC
//! * `lang::integer` handles Integer BASIC
//! * `lang::merlin` handles Merlin assembly language
//! 
//! The language servers are in `bin` and compile to separate executables.  The language servers
//! and CLI both depend on `lang`, but do not depend on each other.
//! 
//! ## Disk Images
//! 
//! Disk image operations are built around three trait objects:
//! * `img::DiskImage` encodes/decodes disk tracks, does not try to interpret a file system
//! * `fs::DiskFS` imposes a file system on the already decoded track data
//!     - don't confuse `std::fs` and `a2kit::fs`
//! * `fs::FileImage` provides a representation of a file that can be restored to a disk image
//! 
//! When a `DiskFS` object is created it takes ownership of some `DiskImage`.
//! It then uses this owned image as storage.  Any changes are not permanent until the
//! image is saved to whatever file system is hosting a2kit.
//! 
//! ### File Systems
//! 
//! In order to manipulate files, `a2kit` must understand the file system it finds on the disk image.
//! As of this writing `a2kit` supports
//! * CP/M 1,2,3
//! * Apple DOS 3.x
//! * FAT (e.g. MS-DOS)
//! * ProDOS
//! * Pascal File System
//! 
//! A simple example follows:
//! ```rs
//! // DiskFS is always mutable because the underlying image can be stateful.
//! let mut disk = a2kit::create_fs_from_file("disk.woz",None)?;
//! // Get a text file from the disk image as a String.
//! let text = disk.read_text("README")?;
//! ```
//! 
//! ### Tracks and Sectors
//! 
//! In order to manipulate tracks and sectors, `a2kit` must understand the way the track data is packed
//! into a disk image.  As of this writing `a2kit` supports
//! 
//! format | platforms | aliases
//! -------|-----------|--------
//! 2MG | Apple II |
//! D13 | Apple II |
//! DO | Apple II | DSK
//! PO | Apple II | DSK
//! IMD | CP/M, FAT |
//! IMG | FAT | DSK, IMA
//! NIB | Apple II |
//! TD0 | CP/M, FAT |
//! WOZ | Apple II |
//! 
//! A simple example follows:
//! ```rs
//! use a2kit::img::{Track,Sector};
//! // DiskImage can be stateful and therefore is always mutable
//! let mut img = a2kit::create_img_from_file("disk.woz")?;
//! // Unlike DiskFS, we cannot access files, only tracks and sectors
//! let sector_data = img.read_sector(Track::Num(0),Sector::Num(0))?;
//! // Disk images are *always* buffered, so writing only affects memory
//! img.write_sector(Track::Num(0),Sector::Num(1),&sector_data)?;
//! // Save the changes to local storage
//! a2kit::save_img(&mut img,"disk.woz")?;
//! ```
//!
//! ### Disk Kinds
//! 
//! Disk kinds are a classification scheme wherein each kind represents the set of all formats
//! that can be handled by a specific hardware or emulation subsystem.  The kinds `a2kit` supports include
//! * Logical ProDOS volumes
//! * 3 inch CP/M formats (Amstrad 184K)
//! * 3.5 inch Apple formats (400K/800K)
//! * 3.5 inch IBM formats(720K through 2880K)
//! * 5.25 inch Apple formats (114K/140K)
//! * 5.25 inch IBM formats (160K through 1200K)
//! * 5.25 inch CP/M formats (Osborne 100K/200K, Kaypro 200K/400K)
//! * 8 inch CP/M formats (IBM 250K, Nabu 1M, TRS-80 600K)
//! 
//! The way a disk kind is identified is by looking for matches to
//! the physical package and track layout, e.g.:
//! ```rs
//! fn test_disk(kind: DiskKind) {
//!     match kind {
//!         DiskKind::D3(_) => panic!("not looking for 3 inch disks"),
//!         DiskKind::D35(_) => panic!("not looking for 3.5 inch disks"),
//!         DiskKind::D525(layout) => println!("layout of 5.25 inch disk is {}",layout),
//!         _ => panic!("something else")
//!     };
//! }
//! ```

pub mod fs;
pub mod lang;
pub mod bios;
pub mod img;
pub mod commands;

use img::DiskImage;
use img::tracks::DiskFormat;
use fs::DiskFS;
use std::io::Read;
use std::fmt::Write;
use log::{warn,info,debug,error};
use regex::Regex;
use hex;

type DYNERR = Box<dyn std::error::Error>;
type STDRESULT = Result<(),Box<dyn std::error::Error>>;

const KNOWN_FILE_EXTENSIONS: &str = "2mg,2img,dsk,d13,do,nib,po,woz,imd,td0,img,ima";
const MAX_FILE_SIZE: u64 = 1 << 26;

/// Save the image file (make changes permanent)
pub fn save_img(disk: &mut Box<dyn DiskFS>,img_path: &str) -> STDRESULT {
    std::fs::write(img_path,disk.get_img().to_bytes())?;
    Ok(())
}

/// Return the file system on a disk image, if all goes well we have `Ok(Some(fs))`.
/// If the file system cannot be identified we have `Ok(None)`.
/// If the file system is identified, but broken, we have `Err(_)`.
/// If `Ok(Some(_))`, the file system takes ownership of the disk image.
fn try_img(mut img: Box<dyn DiskImage>,maybe_fmt: Option<&DiskFormat>) -> Result<Option<Box<dyn DiskFS>>,DYNERR> {
    if let Some(fmt) = maybe_fmt {
        img.change_format(fmt.clone())?;
    }
    if fs::dos3x::Disk::test_img(&mut img,maybe_fmt) {
        info!("identified DOS 3.x file system");
        return Ok(Some(Box::new(fs::dos3x::Disk::from_img(img)?)));
    }
    if fs::prodos::Disk::test_img(&mut img) {
        info!("identified ProDOS file system");
        return Ok(Some(Box::new(fs::prodos::Disk::from_img(img)?)));
    }
    if fs::pascal::Disk::test_img(&mut img) {
        info!("identified Pascal file system");
        return Ok(Some(Box::new(fs::pascal::Disk::from_img(img)?)));
    }
    if fs::fat::Disk::test_img(&mut img) {
        info!("identified FAT file system");
        return Ok(Some(Box::new(fs::fat::Disk::from_img(img,None)?)));
    }
    if fs::fat::Disk::test_img_dos1x(&mut img) {
        info!("identified MS-DOS 1.x file system");
        return Ok(Some(Box::new(fs::fat::Disk::from_img_dos1x(img)?)));
    }
    // For CP/M we have to try various DPB
    let dpb_list = match img.what_am_i() {
        img::DiskImageType::DO | img::DiskImageType::NIB | img::DiskImageType::DOT2MG | img::DiskImageType::WOZ1 => vec![
            bios::dpb::A2_525],
        img::DiskImageType::WOZ2 => vec![
            // 800K CP/M could go here someday
            bios::dpb::A2_525],
        img::DiskImageType::IMD | img::DiskImageType::TD0 => vec![
            bios::dpb::CPM1,
            bios::dpb::SSSD_525,
            bios::dpb::SSDD_525_OFF1,
            bios::dpb::SSDD_525_OFF3,
            bios::dpb::SSDD_3,
            bios::dpb::DSDD_525_OFF1,
            bios::dpb::TRS80_M2,
            bios::dpb::NABU],
        _ => vec![]
    };
    for dpb in &dpb_list {
        if fs::cpm::Disk::test_img(&mut img,dpb,[3,1,0]) {
            info!("identified CP/M file system on {}",dpb);
            return Ok(Some(Box::new(fs::cpm::Disk::from_img(img,dpb.clone(),[3,1,0])?)));
        }
    }
   return Ok(None);
}

/// Given a bytestream return a DiskFS, or Err if the bytestream cannot be interpreted.
/// Optional `maybe_ext` restricts the image types that will be tried based on file extension.
/// Optional `maybe_fmt` can be used to specify a proprietary format (if `None` standard formats will be tried).
pub fn create_fs_from_bytestream(disk_img_data: &Vec<u8>,maybe_ext: Option<&str>,maybe_fmt: Option<&DiskFormat>) -> Result<Box<dyn DiskFS>,DYNERR> {
    let ext = match maybe_ext {
        Some(x) => x.to_string().to_lowercase(),
        None => "".to_string()
    };
    if disk_img_data.len() < 100 {
        return Err(Box::new(img::Error::ImageSizeMismatch));
    }
    debug!("matching image type {}",ext);
    if img::imd::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::imd::Imd::from_bytes(disk_img_data) {
            info!("identified IMD image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::woz1::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::woz1::Woz1::from_bytes(disk_img_data) {
            info!("identified woz1 image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::woz2::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::woz2::Woz2::from_bytes(disk_img_data) {
            info!("identified woz2 image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::dot2mg::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dot2mg::Dot2mg::from_bytes(disk_img_data) {
            info!("identified 2mg image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::td0::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::td0::Td0::from_bytes(disk_img_data) {
            info!("identified td0 image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::nib::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::nib::Nib::from_bytes(disk_img_data) {
            info!("Possible nib/nb2 image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::dsk_d13::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dsk_d13::D13::from_bytes(disk_img_data) {
            info!("Possible D13 image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::dsk_do::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dsk_do::DO::from_bytes(disk_img_data) {
            info!("Possible DO image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::dsk_po::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dsk_po::PO::from_bytes(disk_img_data) {
            info!("Possible PO image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    if img::dsk_img::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dsk_img::Img::from_bytes(disk_img_data) {
            info!("Possible IMG image");
            if let Some(disk) = try_img(Box::new(img),maybe_fmt)? {
                return Ok(disk);
            }
        }
    }
    warn!("cannot match any file system");
    return Err(Box::new(fs::Error::FileSystemMismatch));
}

/// Given a bytestream return a disk image without any file system.
/// Optional `maybe_ext` restricts the image types that will be tried based on file extension.
/// FS heuristics might be invoked if the image type is ambiguous.
pub fn create_img_from_bytestream(disk_img_data: &Vec<u8>,maybe_ext: Option<&str>) -> Result<Box<dyn DiskImage>,DYNERR> {
    let ext = match maybe_ext {
        Some(x) => x.to_string().to_lowercase(),
        None => "".to_string()
    };
    if disk_img_data.len() < 100 {
        return Err(Box::new(img::Error::ImageSizeMismatch));
    }
    debug!("matching image type {}",ext);
    if img::imd::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::imd::Imd::from_bytes(disk_img_data) {
            info!("identified IMD image");
            return Ok(Box::new(img));
        }
    }
    if img::woz1::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::woz1::Woz1::from_bytes(disk_img_data) {
            info!("identified woz1 image");
            return Ok(Box::new(img));
        }
    }
    if img::woz2::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::woz2::Woz2::from_bytes(disk_img_data) {
            info!("identified woz2 image");
            return Ok(Box::new(img));
        }
    }
    if img::dot2mg::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dot2mg::Dot2mg::from_bytes(disk_img_data) {
            info!("identified 2mg image");
            return Ok(Box::new(img));
        }
    }
    if img::td0::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::td0::Td0::from_bytes(disk_img_data) {
            info!("identified td0 image");
            return Ok(Box::new(img));
        }
    }
    if img::nib::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::nib::Nib::from_bytes(disk_img_data) {
            info!("Possible nib/nb2 image");
            return Ok(Box::new(img));
        }
    }
    if img::dsk_d13::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dsk_d13::D13::from_bytes(disk_img_data) {
            info!("Possible D13 image");
            return Ok(Box::new(img));
        }
    }
    // For DO we need to run the FS heuristics to distinguish from PO,
    // in case the extension hint is missing or vague.
    if img::dsk_do::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dsk_do::DO::from_bytes(disk_img_data) {
            info!("Possible DO image");
            if ext=="do" {
                return Ok(Box::new(img));
            }
            if let Ok(Some(_)) = try_img(Box::new(img),None) {
                if let Ok(copy) = img::dsk_do::DO::from_bytes(disk_img_data) {
                    return Ok(Box::new(copy));
                }
            }
            debug!("reject DO based on FS heuristics")
        }
    }
    if img::dsk_po::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dsk_po::PO::from_bytes(disk_img_data) {
            info!("Possible PO image");
            if ext=="po" {
                return Ok(Box::new(img));
            }
            if let Ok(Some(_)) = try_img(Box::new(img),None) {
                if let Ok(copy) = img::dsk_po::PO::from_bytes(disk_img_data) {
                    return Ok(Box::new(copy));
                }
            }
            debug!("reject PO based on FS heuristics")
        }
    }
    if img::dsk_img::file_extensions().contains(&ext) || ext=="" {
        if let Ok(img) = img::dsk_img::Img::from_bytes(disk_img_data) {
            info!("Possible IMG image");
            return Ok(Box::new(img));
        }
    }
    warn!("cannot match any image format");
    return Err(Box::new(img::Error::ImageTypeMismatch));
}

/// buffer a file if its EOF < `max`, otherwise return an error
fn buffer_file(path: &str,max: u64) -> Result<Vec<u8>,DYNERR> {
    let mut f = std::fs::OpenOptions::new().read(true).open(path)?;
    match f.metadata()?.len() <= max {
        true => {
            let mut buf = Vec::new();
            f.read_to_end(&mut buf)?;
            Ok(buf)
        },
        false => Err(Box::new(img::Error::ImageSizeMismatch))
    }
}

/// Calls `create_img_from_bytestream` getting the bytes from stdin.
/// All image types will be tried heuristically.
pub fn create_img_from_stdin() -> Result<Box<dyn DiskImage>,DYNERR> {
    let mut disk_img_data = Vec::new();
    if atty::is(atty::Stream::Stdin) {
        error!("pipe a disk image or use `-d` option");
        return Err(Box::new(commands::CommandError::InvalidCommand));
    }
    std::io::stdin().read_to_end(&mut disk_img_data)?;
    create_img_from_bytestream(&disk_img_data,None)
}

/// Calls `create_img_from_bytestream` getting the bytes from a file.
/// The pathname must already be in the right format for the file system.
/// File extension will be used to restrict image types that are tried,
/// unless the extension is unknown, in which case all will be tried.
pub fn create_img_from_file(img_path: &str) -> Result<Box<dyn DiskImage>,DYNERR> {
    let disk_img_data = buffer_file(img_path,MAX_FILE_SIZE)?;
    let maybe_ext = match img_path.split('.').last() {
        Some(ext) if KNOWN_FILE_EXTENSIONS.contains(&ext.to_lowercase()) => Some(ext),
        _ => None
    };
    create_img_from_bytestream(&disk_img_data,maybe_ext)
}

/// If the path is given call `create_img_from_file`, otherwise call `create_img_from_stdin`
pub fn create_img_from_file_or_stdin(maybe_img_path: Option<&String>) -> Result<Box<dyn DiskImage>,DYNERR> {
    match maybe_img_path {
        Some(img_path) => create_img_from_file(img_path),
        None => create_img_from_stdin()
    }
}

/// Calls `create_fs_from_bytestream` getting the bytes from stdin.
/// All image types and file systems will be tried heuristically.
/// If `maybe_fmt` is `None` deduce a standard format.
pub fn create_fs_from_stdin(maybe_fmt: Option<&DiskFormat>) -> Result<Box<dyn DiskFS>,DYNERR> {
    let mut disk_img_data = Vec::new();
    if atty::is(atty::Stream::Stdin) {
        error!("pipe a disk image or use `-d` option");
        return Err(Box::new(commands::CommandError::InvalidCommand));
    }
    std::io::stdin().read_to_end(&mut disk_img_data)?;
    create_fs_from_bytestream(&disk_img_data, None, maybe_fmt)
}

/// Calls `create_fs_from_bytestream` getting the bytes from a file.
/// The pathname must already be in the right format for the file system.
/// File extension will be used to restrict image types that are tried,
/// unless the extension is unknown, in which case all will be tried.
/// If `maybe_fmt` is `None` deduce a standard format.
pub fn create_fs_from_file(img_path: &str,maybe_fmt: Option<&DiskFormat>) -> Result<Box<dyn DiskFS>,DYNERR> {
    let disk_img_data = buffer_file(img_path,MAX_FILE_SIZE)?;
    let maybe_ext = match img_path.split('.').last() {
        Some(ext) if KNOWN_FILE_EXTENSIONS.contains(&ext.to_lowercase()) => Some(ext),
        _ => None
    };
    create_fs_from_bytestream(&disk_img_data,maybe_ext,maybe_fmt)
}

/// If the path is given call `create_fs_from_file`, otherwise call `create_fs_from_stdin`
fn create_fs_from_file_or_stdin(maybe_img_path: Option<&String>,maybe_fmt: Option<&DiskFormat>) -> Result<Box<dyn DiskFS>,DYNERR> {
    match maybe_img_path {
        Some(img_path) => create_fs_from_file(img_path,maybe_fmt),
        None => create_fs_from_stdin(maybe_fmt)
    }
}

/// Display binary to stdout in columns of hex, +ascii, and -ascii
pub fn display_block(start_addr: usize,block: &Vec<u8>) {
    let mut slice_start = 0;
    loop {
        let row_label = start_addr + slice_start;
        let mut slice_end = slice_start + 16;
        if slice_end > block.len() {
            slice_end = block.len();
        }
        let slice = block[slice_start..slice_end].to_vec();
        let txt: Vec<u8> = slice.iter().map(|c| match *c {
            x if x<32 => '.' as u8,
            x if x<127 => x,
            _ => '.' as u8
        }).collect();
        let neg_txt: Vec<u8> = slice.iter().map(|c| match *c {
            x if x>=160 && x<255 => x - 128,
            _ => 46
        }).collect();
        print!("{:04X} : ",row_label);
        for byte in slice {
            print!("{:02X} ",byte);
        }
        for _blank in slice_end..slice_start+16 {
            print!("   ");
        }
        print!("|+| {} ",String::from_utf8_lossy(&txt));
        for _blank in slice_end..slice_start+16 {
            print!(" ");
        }
        println!("|-| {}",String::from_utf8_lossy(&neg_txt));
        slice_start += 16;
        if slice_end==block.len() {
            break;
        }
    }
}

/// This takes any bytes and makes an ascii friendly string
/// by using hex escapes, e.g., `\xFF`.
/// if `escape_cc` is true, ascii control characters are also escaped.
/// if `inverted` is true, assume we have negative ascii bytes.
/// This is intended for directory strings, for language files use `lang::bytes_to_escaped_string`
pub fn escaped_ascii_from_bytes(bytes: &Vec<u8>,escape_cc: bool,inverted: bool) -> String {
    let mut result = String::new();
    let (lb,ub) = match (escape_cc,inverted) {
        (true,false) => (0x20,0x7e),
        (false,false) => (0x00,0x7f),
        (true,true) => (0xa0,0xfe),
        (false,true) => (0x80,0xff)
    };
    for i in 0..bytes.len() {
        if bytes[i]>=lb && bytes[i]<=ub {
            if inverted {
                result += std::str::from_utf8(&[bytes[i]-0x80]).expect("unreachable");
            } else {
                result += std::str::from_utf8(&[bytes[i]]).expect("unreachable");
            }
        } else {
            let mut temp = String::new();
            write!(&mut temp,"\\x{:02X}",bytes[i]).expect("unreachable");
            result += &temp;
        }
    }
    return result;
}

/// Interpret a UTF8 string as pure ascii and put into bytes.
/// Non-ascii characters are omitted from the result, but arbitrary
/// bytes can be introduced using escapes, e.g., `\xFF`.
/// Literal hex escapes are created by coding the backslash, e.g., `\x5CxFF`.
/// if `inverted` is true the sign of the non-escaped bytes is flipped.
/// if `caps` is true the ascii is put in upper case.
/// This is suitable for either languages or directory strings.
pub fn escaped_ascii_to_bytes(s: &str,inverted: bool,caps: bool) -> Vec<u8> {
    let mut ans: Vec<u8> = Vec::new();
    let hex_patt = Regex::new(r"\\x[0-9A-Fa-f][0-9A-Fa-f]").expect("unreachable");
    let mut hexes = hex_patt.find_iter(s);
    let mut maybe_hex = hexes.next();
    let mut curs = 0;
    let mut skip = 0;
    for c in s.chars() {
    
        if skip>0 {
            skip -= 1;
            continue;
        }
        if let Some(hex) = maybe_hex {
            if curs==hex.start() {
                ans.append(&mut hex::decode(s.get(curs+2..curs+4).unwrap()).expect("unreachable"));
                curs += 4;
                maybe_hex = hexes.next();
                skip = 3;
                continue;
            }
        }
        
        if c.is_ascii() {
            let mut buf: [u8;1] = [0;1];
            if caps {
                c.to_uppercase().next().unwrap().encode_utf8(&mut buf);
            } else {
                c.encode_utf8(&mut buf);
            }
            ans.push(buf[0] + match inverted { true => 128, false => 0 });
        }
        curs += 1;
    }
    return ans;
}

/// Cursor to walk a JSON tree.
pub struct JsonCursor {
    key: Vec<String>,
    sibling: Vec<usize>,
    leaf_key: String
}

impl JsonCursor {
    pub fn new() -> Self {
        Self {
            key: Vec::new(),
            sibling: vec![0],
            leaf_key: String::new()
        }
    }
    /// Walk the tree of a JSON object finding all the leaves.
    /// Any value that is not an object is considered a leaf.
    /// This may be called recursively.
    pub fn next<'a>(&mut self,obj: &'a json::JsonValue) -> Option<(String,&'a json::JsonValue)> {
        assert!(self.key.len()+1==self.sibling.len());
        let depth = self.key.len();
        let pos = self.sibling[depth];
        let mut curr = obj;
        for i in 0..depth {
            curr = &curr[&self.key[i]];
        }
        let mut entry = curr.entries();
        for _i in 0..pos {
            entry.next();
        }
        match entry.next() {
            None => {
                if depth==0 {
                    return None;
                }
                self.key.pop();
                self.sibling.pop();
                return self.next(obj);
            }
            Some((key,val)) => {
                self.sibling[depth] += 1;
                if val.is_object() {
                    self.sibling.push(0);
                    self.key.push(key.to_string());
                    return self.next(obj);
                }
                self.leaf_key = key.to_string();
                return Some((key.to_string(),val));
            }
        }
    }
    pub fn parent<'a>(&self,obj: &'a json::JsonValue) -> Option<&'a json::JsonValue> {
        assert!(self.key.len()+1==self.sibling.len());
        let depth = self.key.len();
        if depth==0 {
            return None;
        }
        let mut curr = obj;
        for i in 0..depth {
            curr = &curr[&self.key[i]];
        }
        Some(curr)
    }
    /// Return key to current leaf as list of strings.
    /// Note this includes the key that is returned with `next`.
    pub fn key_path(&self) -> Vec<String> {
        let mut ans: Vec<String> = Vec::new();
        for i in 0..self.key.len() {
            ans.push(self.key[i].clone())
        }
        ans.push(self.leaf_key.clone());
        ans
    }
    /// Return key to current leaf as a path string.
    /// This can have problems in case there are keys containing `/`,
    /// so `key_path` should always be preferred.
    pub fn key_path_string(&self) -> String {
        let mut ans = String::new();
        for i in 0..self.key.len() {
            ans += "/";
            ans += &self.key[i];
        }
        ans += "/";
        ans += &self.leaf_key;
        ans
    }
}

#[test]
fn test_json_cursor() {
    let mut curs = JsonCursor::new();
    let s = "{
        \"root_str\": \"01\",
        \"obj1\": {
            \"list1\": [1,3,5],
            \"str1\": \"hello\"
        },
        \"num1\": 1000,
        \"obj2\": {
            \"null1\": null
        }
    }";
    let obj = json::parse(s).expect("could not parse test string");
    let mut leaves: Vec<(String,&json::JsonValue,Vec<String>)> = Vec::new();
    while let Some((key,leaf)) = curs.next(&obj) {
        leaves.push((key,leaf,curs.key_path()));
    }
    assert_eq!(leaves.len(),5);

    assert_eq!(leaves[0].0,"root_str");
    assert_eq!(leaves[0].1.as_str().unwrap(),"01");
    assert_eq!(leaves[0].2,vec!["root_str"]);

    assert_eq!(leaves[1].0,"list1");
    assert!(leaves[1].1.is_array());
    assert_eq!(leaves[1].2,vec!["obj1","list1"]);

    assert_eq!(leaves[2].0,"str1");
    assert_eq!(leaves[2].1.as_str().unwrap(),"hello");
    assert_eq!(leaves[2].2,vec!["obj1","str1"]);

    assert_eq!(leaves[3].0,"num1");
    assert_eq!(leaves[3].1.as_u16().unwrap(),1000);
    assert_eq!(leaves[3].2,vec!["num1"]);

    assert_eq!(leaves[4].0,"null1");
    assert!(leaves[4].1.is_null());
    assert_eq!(leaves[4].2,vec!["obj2","null1"]);
}