Interactive Debugger

The Daffodil Command Line Interface (CLI) comes with a built-in interactive debugger that pauses parsing/unparsing and allows for user inspection of some internal state. To start Daffodil in debugger mode, provide the global --debug option, for example:

daffodil --debug parse --schema schema.dfdl.xsd input.dat

Enabling the debugger displays a (debug) prompt, at which point various commands can be entered to control parsing and inspect Daffodil state. Note that you can optionally provide a file to the --debug option. Each line in the file is provided to the debugger as if it were typed by the user. Below is the list of commands accepted by the debugger and their descriptions.

break <element_id>

Create a breakpoint, causing the debugger to stop when the element with the <element_id> name is created.

break foo

Abbreviation: b

clear

Clear the screen.

Abbreviation: c

complete

Continue parsing the input data until parsing is complete. All breakpoints are ignored.

Abbreviation: comp

condition <breakpoint_id> <dfdl_expression>

Set a condition on a specified breakpoint. When a breakpoint is encountered, the debugger only pauses if the DFDL expression evaluates to true. If the result of the DFDL expressions is not a boolean value, it is treated as false.

Abbreviation: cond

condition 1 dfdl:occursIndex() eq 3
continue

Continue parsing the input data until a breakpoint is encountered. At which point, pause parsing and display a debugger console to the user.

Abbreviation: c

delete <type> <id>

Remove a breakpoint or display. Valid values for <type> are breakpoint and display.

Abbreviation: d

delete breakpoint 1
delete display 1
disable <type> <id>

Disable a breakpoint or display. Valid values for <type> are breakpoint and display.

Abbreviation: dis

disable breakpoint 1
disable display 1
display <debugger_command>

Execute a debugger command every time a debugger console is displayed to the user.

Abbreviation: di

display info infoset
enable <type> <id>

Enable a breakpoint or display. Valid values for <type> are breakpoint and display.

Abbreviation: e

enable breakpoint 1
enable display 1
eval <dfdl_expression>

Evaluate a DFDL expression. If the expression evaluates to a complex element, then the XML representation for the complex element is displayed. If the expression evaluates to a simple type, then the value of the simple type is display.

Abbreviation: ev

eval dfdl:occursIndex()
eval /ex:file/line[1]
help [command]

Display help. If a command is given, display help information specific to that command and its subcommands.

Abbreviation: h

history [outfile]

Display the history of commands. If an argument is given, write the history to the specified file rather then printing it to the screen.

Abbreviation: hi

info <item>...

Print internal information to the console. <item> can be specified multiple times to display multiple pieces of information.

Abbreviation: i

info data infoset

The valid items are:

arrayIndex

Display the current array limit. Abbreviation: ai

bitLimit

Display the current bit limit. Abbreviation: bl

bitPosition

Display the current bit position. Abbreviation: bp

breakpoints

Display the list of breakpoints. Abbreviation: b

childIndex

Display the child index. Abbreviation: ci

data

Display the input data. Abbreviation: d

delimiterStack

Display the current delimiter stack. Abbreviation: ds

diff

Display the differences from the previous state.

discriminator

Display whether or not a discriminator is set. Abbreviation: dis

displays

Display the current display expressions. Abbreviation: di

foundDelimiter

Display the most recently found delimiter. Abbreviation: fd

groupIndex

Display the current group index. Abbreviation: gi

infoset

Display the current infoset. Abbreviation: i

occursBounds

Display the current occurs bounds. Abbreviation: ob

parser

Display the current parser. Abbreviation: p

path

Display the current schema component designator/path.

unparser

Display the current unparser. Abbreviation: u

quit

Immediately abort all processing.

Abbreviation: q

set <setting> <value>
Change a debugger setting.
set dataLength -1
set wrapLength 50
set removeHidden true

Valid settings are:

breakOnFailure <boolean>

Set whether or not the debugger should break on failures. If set to false the normal processing occurs. If set to true, any errors cause a break. Note that due to the backtracking behavior, not all failures are fatal. Defaults to false.

breakOnlyOnCreation <boolean>

Set whether or not breakpoints should only be evaluated on element creation. Must be either true/false or 1/0. If true, breakpoints only stop on element creation. If false, breakpoints stop anytime a parser interacts with an element. Defaults to true.

dataLength <integer>

Set the number of bytes to display when displaying input data. If negative, display all input data. This only affects the info data command. Defaults to 70.

infosetLines <integer>

Set the maximum number of lines to display when displaying the infoset. This only affects the info infoset command. This shows the last number of lines of the infoset. If the number is less than or equal to zero, the entire infoset is printed. Defaults to -1.

removeHidden <boolean>

Set whether or not hidden elements (e.g through the use of dfdl:hiddenGroupRef) should be displayed. This effects the eval and info infoset commands. Must be either true/false or 1/0. Defaults to false.

representation <string>

Set the output when displaying data. Must be either text` orbinary. Defaults totext``.

wrapLength <integer>

Set the number of characters at which point output wraps. This only affects the info data and info infoset commands. A length less than or equal to zero disables wrapping. Defaults to 80.

step

Perform a single parse action, pause parsing, and display a debugger prompt.

Abbreviation: s

trace

Continue parsing the input data until a breakpoint is encountered, while running display commands after every parse step. When a breakpoint is encountered, pause parsing and display a debugger console to the user.

Abbreviation: t