Documentation

The internal system state consists of a list of name-value pairs of type (String, XmlTrees), so arbitrary lists of trees can be stored. For options, often only strings are used as values, so a set of access functions with string values is available The error handling method can be controlled by an error handler filter, the default filter issues the errors on stderr

The State has a system and a user part the user state is a type parameter

The monad type for commands. It is an instance of StateIO from the general module Control.Monad.MonadStateIO.

The XmlFilter type for filters working on a state

change the user state

• 1.parameter fct : the user state change function
• returns : the new state

set the user state.

• 1.parameter s : the new state
• returns : the new state

read the user state

• returns : the current state

change the system part of the state.

see also : changeState

set the system part of the state.

see also : setState

read the system part of the state.

see also : getState

the initial system state

an empty list of attribute value pairs

change the attributes in the system state

set the error message handler

get the error handler

set or change a single system parameter.

• 1.parameter name : the name of the parameter
• 2.parameter value : the list of associated trees
• returns : nothing

see also : setSysParam, setSysParamInt

set or change a single system parameter of type string.

• 1.parameter name : the name of the parameter
• 2.parameter value : the (new) string value
• returns : nothing

see also : setSysParamTree, setSysParamInt

set or change a single integer type system parameter

see also : setSysParam

add (or change) all attributes of the document root to the system state - returns : this

read a system parameter

• 1.parameter name : the name of the parameter
• returns : the list of tres associated with the key, or the empty list for unknown parameters

read a system string parameter

• 1.parameter name : the name of the parameter
• returns : the value, or the empty string for unknown parameters

read a system parameter or return a default value

• 1.parameter name : the name of the parameter
• 2.parameter default : the default value
• returns : the value if found, else the default

read an integer system parameter

• 1.parameter name :
• 2.parameter default :

see also : getSysParamWithDefault

exec a XState command with initial state.

• 1.parameter initalState : the inital user state
• 2.parameter cmd : the command
• returns : the i/o command with result and user state

exec a XState command with initial user state. ignore final user state. like run0, but ignore the resulting user state

exec a XState command in th IO monad. like run with the empty state ().

run a command in a new user state. chain the system state part, init new system state with the current one, run the command and update the old system state with the resulting new system state

• 1.parameter initialUserState : the initial user state
• 2.parameter cmd : the command
• returns : the result of executing cmd and the final state

like chain' but forget the final user state

• 1.parameter initialUserState : the initial user state
• 2.parameter cmd : the command
• returns : only the result of executing cmd

lift a XmlFilter to a XmlStateFilter filter issue all error nodes as error messages and remove the error nodes from the result

• 1.parameter f : the filter
• returns : the filter running in the state monad

all errors are filtered from the result and issued on stderr

lift an I/O command

• 1.parameter cmd : the i/o command
• returns : the i/o command lifted to the XML state monad

set the trace level.

convention:

0: no trace output (default)

1: trace important computation steps, e.g. accessing a document

2: trace small computation steps

3: output an intermediate result XmlTree in XML source format

4: output an intermediate result XmlTree in tree representation

• 1.parameter level : the trace level
• returns : nothing

get the current trace level.

• returns : the current trace level

trace output for arbitray commands.

• 1.parameter level : the trace level, for which the command will be execuded if level <= current trace level
• 2.parameter cmd : the command to be executed
• returns : nothing

trace output function for simple text.

• 1.parameter level : like in traceCmd
• 2.parameter str : the test
• returns : nothing

trace output of the user part of the program state.

• 1.parameter level : like in traceCmd
• 2.parameter showFct : the toString function
• returns : nothing

filter to reset the state attribute a_status - returns : this

report an error message.

• returns : if the input tree n represents an error, res = [] and the error is processed by the errror handler filter (default: error is issued on stderr) else res = [n]

see also : issueErr

set the error level in system state

default error handler for writing errors to stderr

error message handler for collecting all error messages all messages are stored under attribute a_error_log they can be read with getSysParamTree a_error_log or by applying the filter getErrorMsg to the root node

the filter for reading all collected error mesages

result is the list of error messages, the input tree is ignored

error level translation c_warn (1) : warning, c_err (2): error (e.g. parse error, validation error, ...), c_fatal (3) : fatal error (document access error, internal error, ...)

short cut for issuing a warning

see also : issueError, issueErr

short cut for issuing an error

see also : issueError

short cut for issuing a fatal error

see also : issueError, issueErr

checks the value of the attribute a_status in a document root. if it contains a value greater or equal to c_err, an error with error message stored in attribute a_module is issued and the filter acts as the noneM filter else its the thisM filter

add the error level and the module where the error occured to the attributes of a document root node and remove the children when level is greater or equal to c_err

check whether tree is a document root and the status attribute has a value less than c_err

check whether the error level attribute in the system state is set to error, in this case the children of the document root are removed and error info is added as attributes with setStatus else nothing is changed

monadic filter for processing the attribute list of a tag. for other trees this filter acts like noneM

see also : processAttr, processAttrl