🟠XmlConverter.hs

Module Documentation: XmlConverter

The XmlConverter module in Haskell is dedicated to converting between XML data and a custom Doc data structure defined in the Types module. It provides functionalities to parse XML into Doc and serialize Doc structures back into XML format, facilitating document processing within applications that interact with XML data.

Interface and Functionality Overview

Imported Modules

• XmlParser: Utilizes the parseXmlFile function to parse XML content into an XmlValue data structure.

• Types: Imports the Doc and defaultDoc definitions to construct and manipulate document structures.

Core Functions

xmlValueToDoc

• Purpose: Converts an XmlValue to a Doc structure by mapping XML elements and attributes to Doc properties.

• Parameters: XmlValue - the XML data to be converted.

• Returns: Doc - the resulting document structure.

xmlToDoc

• Purpose: Public interface to convert XML string data into a Doc structure, handling parsing and conversion errors.

• Parameters: String - XML content as a string.

• Returns: Either String Doc - either an error message or the successfully converted document.

docToXmlString

• Purpose: Serializes a Doc structure into a properly indented XML string.

• Parameters:

  • doc: The Doc structure to serialize.

  • indentLvl: The current indentation level, used to format the XML output properly.

• Returns: String - the XML representation of the Doc.

Detailed Conversion Logic

• XML to Doc Conversion: Parses XML elements and attributes, applying them to the corresponding fields in the Doc structure. Special handling for document components like headers, links, and lists ensures that the XML structure is faithfully represented.

• Doc to XML Serialization: Constructs XML elements from Doc properties, applying indentation for readability and preserving the document structure through nested tags and attributes.

Conclusion

The XmlConverter module is crucial for applications requiring robust XML handling capabilities, allowing for seamless transitions between XML formats and structured document data. This facilitates a wide range of applications, from data interchange to configuration management and content processing.

module XmlConverter (xmlToDoc, docToXmlString) where

import XmlParser (XmlValue(..), parseXmlFile)
import Types (Doc(..), defaultDoc)
import Data.Maybe (fromMaybe)

xmlValueToDoc :: XmlValue -> Doc
xmlValueToDoc (XmlElement "document" _ children) =
    defaultDoc { isDocument = True }
        { list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "header" attrs children) =
    let title = fromMaybe "" (lookup "title" attrs)
    in defaultDoc { isHeader = True, isTitle = True, string = title,
    list = map xmlValueToDoc children}
xmlValueToDoc (XmlElement "author" _ children) =
    defaultDoc { isAuthor = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "date" _ children) =
    defaultDoc { isDate = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "bold" _ children) =
    defaultDoc { isBold = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "underlined" _ children) =
    defaultDoc { isUnderlined = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "italic" _ children) =
    defaultDoc { isItalic = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "code" _ children) =
    defaultDoc { isCode = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "body" _ children) =
    defaultDoc { isBody = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "paragraph" _ children) =
    defaultDoc { isParagraph = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "section" attrs children) =
    let title = fromMaybe "" (lookup "title" attrs)
    in defaultDoc { isSection = True, isTitle = True, string = title,
    list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "codeblock" _ children) =
    defaultDoc { isCodeBlock = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "list" _ children) =
    defaultDoc { isList = True, list = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "link" attrs children) =
    let url = fromMaybe "" (lookup "url" attrs)
    in defaultDoc { isLink = True, link = url, list
     = map xmlValueToDoc children }
xmlValueToDoc (XmlElement "image" attrs children) =
    let url = fromMaybe "" (lookup "url" attrs)
    in defaultDoc { isImage = True, image = url, list =
         map xmlValueToDoc children }
xmlValueToDoc (XmlText text) =
    defaultDoc { isString = True, string = text }
xmlValueToDoc _ = defaultDoc

xmlToDoc :: String -> Either String Doc
xmlToDoc myString = case parseXmlFile myString of
    Nothing -> Left "Cannot parse"
    Just a -> case xmlValueToDoc a of
        Doc{isDocument = False} -> Left "Cannot parse"
        d -> Right d

docToXmlString :: Doc -> Int -> String
docToXmlString doc indentLvl
    | isDocument doc = i ++ "<document>\n" ++ x ++ i ++ "</document>\n"
    | isHeader doc = i ++ headerToXmlString doc indentLvl
    | isAuthor doc = i ++ "<author>" ++ x ++ "</author>\n"
    | isDate doc = i ++ "<date>" ++ x ++ "</date>\n"
    | isBody doc = i ++ "<body>\n" ++ x ++ i ++ "</body>\n"
    | otherwise = docToXmlString2 doc indentLvl
    where
        i = replicate (indentLvl * 4) ' '
        x = concatMap (\d -> docToXmlString d (indentLvl + 1)) (list doc)

docToXmlString2 :: Doc -> Int -> String
docToXmlString2 doc indentLvl
    | isSection doc = i ++ sectionToXmlString doc indentLvl
    | isParagraph doc = i ++ "<paragraph>" ++ x ++ "</paragraph>\n"
    | isCodeBlock doc = i ++ "<codeblock>\n" ++ x ++ i ++ "</codeblock>\n"
    | isList doc = i ++ "<list>\n" ++ x ++ i ++ "</list>\n"
    | isLink doc = "<link url=\"" ++ link doc ++ "\">" ++ x ++ "</link>"
    | otherwise = docToXmlString3 doc indentLvl
    where
        i = replicate (indentLvl * 4) ' '
        x = concatMap (\d -> docToXmlString d (indentLvl + 1)) (list doc)

docToXmlString3 :: Doc -> Int -> String
docToXmlString3 doc indentLvl
    | isImage doc = "<image url=\"" ++ image doc ++ "\">" ++ x ++ "</image>"
    | isBold doc = "<bold>" ++ x ++ "</bold>"
    | isUnderlined doc = "<underlined>" ++ x ++ "</underlined>"
    | isItalic doc = "<italic>" ++ x ++ "</italic>"
    | isCode doc = "<code>" ++ x ++ "</code>"
    | otherwise = docToXmlString4 doc indentLvl
    where
        x = concatMap (\d -> docToXmlString d (indentLvl + 1)) (list doc)

docToXmlString4 :: Doc -> Int -> String
docToXmlString4 doc _
    | isString doc = string doc
    | otherwise = ""

headerToXmlString :: Doc -> Int -> String
headerToXmlString doc indentLvl =
    let indent = replicate (indentLvl * 4) ' '
        content = concatMap (\d -> docToXmlString d (indentLvl + 1)) (list doc)
    in  "<header title=\"" ++ string doc ++ "\">\n" ++
    content ++ indent ++ "</header>\n"

sectionToXmlString :: Doc -> Int -> String
sectionToXmlString doc indentLvl =
    let indent = replicate (indentLvl * 4) ' '
        content = concatMap (\d -> docToXmlString d (indentLvl + 1)) (list doc)
    in  "<section title=\"" ++ string doc ++ "\">\n" ++ content ++
    indent ++ "</section>\n"