org.hd.d.pg2k.svrCore
Class ExhibitName

java.lang.Object
  org.hd.d.pg2k.svrCore.ExhibitName

public final class ExhibitName
extends java.lang.Object

Routines to validate/parse an exhibit name. An exhibit name is a (relative) path name in a filesystem representation, and a (relative) URL in a Web presentation.

This is based on the assumption that we use the String name everywhere as a sort of universal currency, rather than pre-parsing everything as in the old Attributes.ItemName.

The syntax of the file name is:

1. A category directory name (consisting of characters from the range [a-z-_] starting with a character in the range [a-z]
2. Zero or more directory components of the form _more[0-9A-Z]*
3. A final unique `file' name consisting of hyphen-separated words ending with a recognised extension that indicates the MIME type of the underlying file; full details of the syntax of this part are given below.

The syntax of a Gallery image name is as follows: {word-}+{discardableword-}*[number-]AUTH.ext where word is an alphanumeric sequence containing at least one letter (there must be at least one such word in the name), discardableword is like word in syntax but comes from a small list of words that can trail the main image description and indicate some gross features of the image, eg `bg' and `mono' (these words are optional and will only be recognised as discardable if after all non-discardable words), number is a optional decimal number consisting purely of the digits 0-9 (with any leading zeros ignored rather than indicating octal), AUTH being the all-upper-case all-alpha author's initials (this is compulsory), and ext being the extension indicating the image type(this is compulsory).

Note that other than the extension, all components are delimited by dashes, and there must be no spaces in the name. The extension may contain dots, and dots are not allowed elsewhere in the name.

For the purposes of sorting, the sort order is first by the [word-]+ portion (ASCII order), then by the author (ASCII order), then by the number portion (numerically), then by the {discardableword-}* portion (ASCII order), then by the extension (ASCII order).

It is possible to build a ParsedName which is split into its consitituent parts, and is Comparable with the sort order given above.

WORD_SEP

public static final char WORD_SEP

The character used to separate words.

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WORD_SEPS

public static final java.lang.String WORD_SEPS

The character used to separate words as a string.

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MAX_NAME_LENGTH

public static final int MAX_NAME_LENGTH

Maximum valid name length. This is basically limited by maximum URL and UNIX-filename length, and the fact that we need some "decoration" overhead of exhibit names when enbedded in filenames, URLs, etc.

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_minFileLen

private static final int _minFileLen

Minimum length of file component of any valid name. Such a minimal name must be of the form ``a-A.a''. In practice any real name must be longer since we will not have one-character author initials nor file extensions, but this will help us quickly discard directory entries such as ``.'' and ``..'' for example.

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MIN_NAME_LENGTH

public static final int MIN_NAME_LENGTH

Minimum valid name length. Of form "a/a-A.a".

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MAX_WORD_LENGTH

public static final int MAX_WORD_LENGTH

Maximum allowable length of any single word. This is where the name is of the form a/word-A.a.

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MAX_STEM_LENGTH

public static final int MAX_STEM_LENGTH

Maximum allowable length of any name stem (ie just main words). This is where the name is of the form a/stem-A.a where the stem is one or more words.

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MAX_ATTR_WORD_LENGTH

public static final int MAX_ATTR_WORD_LENGTH

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intermediateDirPrefix

public static final java.lang.String intermediateDirPrefix

Prefix of intermediate directory components in name.

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_iDirPrefixLen

private static final int _iDirPrefixLen

Length of prefix of intermediate directory components in name.

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MIN_AUTH_INITIALS_LENGTH

public static final int MIN_AUTH_INITIALS_LENGTH

Minimum length of author-initial component; strictly positive.

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MAX_AUTH_INITIALS_LENGTH

public static final int MAX_AUTH_INITIALS_LENGTH

Maximum length of author-initial component.

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SIMPLE_SMART_ORDER

public static final java.util.Comparator<java.lang.String> SIMPLE_SMART_ORDER

A simple invariant comparator that sorts (String) full exhibit names in a human-friendly order. This is essentially a case-insensitive sort on the file component.

Ties are broken by a normal String lexical ordering on the full names.

Discardable/attribute words are not discarded nor otherwise treated specially for this comparison.

NO_ATTR_WORDS

private static final java.util.SortedSet<java.lang.String> NO_ATTR_WORDS

Immutable empty attribute word set.

ExhibitName

public ExhibitName()

validNameInitialComponentSyntax

public static boolean validNameInitialComponentSyntax(java.lang.String initialNameComponent,
                                                      int len)

Validates the syntax of the first component of a name; returns true if valid. This is helpful to identify the roots of a directory scan, for example.

This ignores any characters from len onwards, so the portion from 0--len-1 must be a complete valid initial directory, and the string passed must be at least len characters long.

Designed to be efficiently callable from validNameSyntax() without requiring creation of any objects.

validAuthorSyntax

public static boolean validAuthorSyntax(java.lang.String s,
                                        int start,
                                        int end)

Validates a set of author's initials for syntax; returns true if valid. This version examines part of a string.

Characters from start to end-1 are checked.

The start and end positions must be valid in the String passed and start start must come before end.

Returns false if the string is null.

Parameters:

s - the value to be examined

start - the starting position of the author; must be valid offset within string

end - just after the end of the author; must be greater than start and no greater than the string length

validAuthorSyntax

public static boolean validAuthorSyntax(java.lang.String s)

Validates a set of author's initials for syntax; returns true if valid. The whole string must be a valid author ID (and not null).

Returns:

true iff s is not null and is a valid set of author initials

validWord

public static boolean validWord(java.lang.String s)

Checks that the String passed to it is a valid word (main or attribute). This means it must be non-zero length (and non-null), and consist only of letters and digits.

validAttributeWord

public static boolean validAttributeWord(java.lang.String s)

Checks that the String passed to it is a valid attribute word. This means it must be non-zero length (and non-null), and consist only of letters and digits and must not consist entirely of digits or upper-case letters (to avoid ambiguity with the number-in-series value and author).

Maximum attribute word must be at most long enough to allow for a single-letter main word and dash, so is two less than the longest allowable main word.

validNameInitialComponentSyntax

public static boolean validNameInitialComponentSyntax(java.lang.String initialNameComponent)

Validates the syntax of the first component of a name; returns true if valid. This is helpful to identify the roots of a directory scan, for example.

validWordCharacter

public static boolean validWordCharacter(char c)

Returns true if the character passed is a valid word character. A valid word character is an ASCII digit or letter (either case).

We test the most common cases first for speed.

validNameFinalComponentSyntax

public static boolean validNameFinalComponentSyntax(java.lang.String finalNameComponent)

Validates the syntax of the last component of a name; returns true if valid. This is helpful when running a directory scan, for example.

This does not check that the author's initials or the extension are actually acceptable other than that they are syntactically valid.

validNameSyntaxBasic

public static boolean validNameSyntaxBasic(java.lang.String name)

Very quick basic set of name validity checks; returns true if valid. Very quick constant-time checks that the name is not null and is of a legitimate length.

validNameSyntax

public static boolean validNameSyntax(java.lang.String name)

Fully validates the syntax of a name; returns true if valid. It attempts to be fast and to not create too many intermediate/temporary objects.

This does not attempt to check a name against current databases nor return any parsed components.

getFileComponent

public static java.lang.String getFileComponent(java.lang.String fullExhibitName)

Extract the file component (short name) of a full exhibit name, assuming the name is valid. Two exhibits should always be distinguishable by this component, also known as the "short" name.

If the argument is not a valid full exhibit name, the result is undefined.

getCategoryComponent

public static java.lang.String getCategoryComponent(java.lang.String fullExhibitName)

Extract the category component (top directory) of a full exhibit name, assuming the name is valid. If the argument is not a valid full exhibit name, the result is undefined.

getDirComponent

public static java.lang.String getDirComponent(java.lang.String fullExhibitName)

Extract the full directory component of a full exhibit name, assuming the name is valid. This does not include the trailing directory separator.

If the argument is not a valid full exhibit name, the result is undefined.

getVirtualExhibitName

public static java.lang.String getVirtualExhibitName(java.lang.String fullExhibitName)

Get the "virtual" name consisting of the category directory and then the file component. The results is a syntactically-valid full exhibit name, but omits the internal directory "noise".

If the argument is not a valid full exhibit name, the result is undefined.

getMainAndAttrWordComponentBoundaries

public static int[] getMainAndAttrWordComponentBoundaries(java.lang.String fullExhibitName,
                                                          java.util.Set<java.lang.String> allAttrWords)

Find end of main stem and of attribute words of the supplied full exhibit name. This returns a three-element array, of which:

• Element 0 is the position of the separator immediately before the first main word (a '/').
• Element 1 is the position (index in the input String) of the separator immediately following the final word of the main stem of the exhibit name. All the words of the main stem precede it, and any attribute words and number-in-series value follow it.
• Element 2 of the result is the position (index in the input String) of the separator immediately following the final attribute word of the exhibit name. (If there are no attribute words this will be the same value as element 1.) Any number-in-series value follows it.

This has to be passed a set of all valid attribute words (as Strings which meet the requirements of validAttributeWord()) to be able to compute this boundary.

If the argument is not a valid full exhibit name, the result is undefined.

Parameters:

allAttrWords - a Set of all legal attribute words (String values); can be empty but not null

getMainWordsComponent

public static java.lang.String getMainWordsComponent(java.lang.String fullExhibitName,
                                                     java.util.Set<java.lang.String> allAttrWords)

Extract the main words (stem) component of a full exhibit name, assuming the name is valid; never null nor empty. There is always at least one main word; so the result is always non-null and non-empty.

(This does not end nor start with a separator.)

If the argument is not a valid full exhibit name, the result is undefined.

Parameters:

allAttrWords - a Set of all legal attribute words (String values)

getMainWords

public static java.util.Enumeration<?> getMainWords(java.lang.String fullExhibitName,
                                                    java.util.Set<java.lang.String> allAttrWords)

Return Enumeration over main words; never null, never empty if the name is well-formed. Uses StringTokenizer.

getAttributeWordsComponent

public static java.lang.String getAttributeWordsComponent(java.lang.String fullExhibitName,
                                                          java.util.Set<java.lang.String> allAttrWords)

Extract the attribute words component of a full exhibit name, assuming the name is valid. If there are no attribute words this returns null, else the result is non-empty and is the fragment of the full name containing the attribute word with the words separated as usual.

If the argument is not a valid full exhibit name, the result is undefined.

Parameters:

allAttrWords - a Set of all legal attribute words (String values)

getAttributeWordsComponentEnumeration

public static java.util.Enumeration<?> getAttributeWordsComponentEnumeration(java.lang.String fullExhibitName,
                                                                             java.util.Set<java.lang.String> allAttrWords)

Extract the attribute words component of a full exhibit name as an Enumeration of String, assuming the name is valid. If there are no attribute words this returns null, else the result is non-empty and is an Enumeration of String values of the attributes in order.

If the argument is not a valid full exhibit name, the result is undefined.

Parameters:

allAttrWords - a Set of all legal attribute words (String values)

getAttributeWordsComponentSortedSet

public static java.util.SortedSet<java.lang.String> getAttributeWordsComponentSortedSet(java.lang.String fullExhibitName,
                                                                                        java.util.Set<java.lang.String> allAttrWords)

Extract the attribute words component of a full exhibit name as a SortedSet of String, assuming the name is valid; never null. If there are no attribute words this returns a (fixed, immutable) empty set.

Duplicates attribute words are automatically eliminated

If the argument is not a valid full exhibit name, the result is undefined.

Parameters:

allAttrWords - a Set of all legal attribute words (String values)

Returns:

non-null, de-duped, alpha-sorted attribute words from the name

getNumberInSeriesComponentAsString

public static java.lang.String getNumberInSeriesComponentAsString(java.lang.String exhibitName)

Extract the number-in-series component of a full exhibit name as a String, assuming the name is valid. If the argument is not a valid full exhibit name, the result is undefined unless the name is the final (file) component of a valid name.

A missing number-in-series value causes us to return null.

This is:

• the final word before the author initials,
• must consist entirely of digits,
• is always non-negative,
• is always to be interpretted in radix 10, so "010" = "10" = 10 (ie ten),
• and is not the only word.

getNumberInSeriesComponent

public static int getNumberInSeriesComponent(java.lang.String fullExhibitName)

Extract the number-in-series component of a full exhibit name as a non-negative int, assuming the name is valid. If the argument is not a valid full exhibit name, the result is undefined.

A missing number-in-series value causes us to return zero.

This is:

• the final word before the author initials,
• must consist entirely of digits,
• is always non-negative,
• is always to be interpretted in radix 10, so "010" = "10" = 10 (ie ten),
• and is not the only word.

Returns:

positive number-in-series value, or zero if absent

getAuthorComponent

public static java.lang.String getAuthorComponent(java.lang.String exhibitName)

Extract the author component of a full exhibit name, assuming the name is valid. If the argument is not a valid full exhibit name, the result is undefined unless the name is the final (file) component of a valid name.

getExtensionComponent

public static java.lang.String getExtensionComponent(java.lang.String exhibitName)

Extract the extension (without dot) of a full exhibit name, assuming the name is valid. If the argument is not a valid full exhibit name, the result is undefined unless the name is the final (file) component of a valid name.