class resolve_as_file :Reads from the local file system.?file_prefix:[ `Allowed | `Not_recognized | `Required ] -> ?host_prefix:[ `Allowed | `Not_recognized | `Required ] -> ?system_encoding:Pxp_types.encoding -> ?map_private_id:Pxp_types.private_id -> Neturl.url -> ?open_private_id:Pxp_types.private_id ->
Pervasives.in_channel * Pxp_types.encoding option -> ?base_url_defaults_to_cwd:bool -> ?not_resolvable_if_not_found:bool -> unit ->resolver
file URL's are interpreted as
 file names of the local file system, and the referenced files are opened.
 The full form of a file URL is: file://host/path, where
 host specifies the host system where the file identified path
 resides. host="" or host="localhost" are accepted; other values
 will raise Not_competent. The standard for file URLs is
 defined in RFC 1738.
 Option file_prefix: Specifies how the file: prefix of file names
 is handled:
`Not_recognized: The prefix is not recognized.`Allowed:        The prefix is allowed but not required (the default).`Required:       The prefix is required.host_prefix: Specifies how the //host phrase of file names
 is handled:`Not_recognized: The phrase is not recognized.`Allowed:        The phrase is allowed but not required (the default).`Required:       The phrase is required.system_encoding: Specifies the encoding of file names of
 the local file system. Default: UTF-8.
 Options map_private_id and open_private_id: These options are
 deprecated and no longer described here.
 Option base_url_defaults_to_cwd: If true, relative URLs
 are interpreted relative to the current working directory at the time
 the class is instantiated, but only if there is no parent URL, i.e.
 rid_system_base=None. If false (the default), such URLs cannot be resolved.
 In general, it is better to set this option to false, and to
 initialize rid_system_base properly.
 Option not_resolvable_if_not_found: If true (the default), 
 "File not found" errors stop the resolution process. If false,
 "File not found" is treated as Not_competent.
