31/35 test passed version. inverted list for selec
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When inserting a row we don't put a + sign before the name
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When we return row of an empty table instead of having [] we have [_] same thing with drop
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Currently a condtion in a query as to contain no space in order to function properly
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Ex: the condtion +name="Dakota" will work but the conditions +name = "Dakota" or
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+name="North Dakota" will not.
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solution.pl
76
solution.pl
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:- use_module(library(dcg/basics)).
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% DCG rule that checks if the remainder of the input
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% starts with Delim (a list), but does not consume
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% any input.
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lookahead(Delim , L, L) :-
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prefix(Delim , L).
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% Checks if the remainder of the input starts with one
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% of the items in the supplied list (as per lookahead /3).
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lookaheads([H|T]) -->
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lookahead(H), ! ; lookaheads(T).
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% Reads text until one of the delimiters in Delims is
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% encountered , then unifies R with the Prolog term parsed
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% from the text.
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% ! Will crash the parse if a delimiter is encountered
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% but the intervening text is not a Prolog term (you
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% don’t have this handle this case).
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prolog_term(R, Delims) -->
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string(S), lookaheads(Delims), !, {
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read_term_from_atom(S, R, []) }.
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/**
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* Authors:
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* Dubois Brieuc
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* Dubois Simon
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*/
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:- dynamic tables/0.
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/*
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Prints the names of all existing tables, one per line (use writeln/1).
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Prints the names of all existing tables, one per line (using writeln/1).
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A table name is always an atom.
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*/
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tables :- tabl(X, _), writeln(X).
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@ -38,9 +22,8 @@ tables(Tables) :- findall(X, tabl(X, _), Tables).
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When this predicate is executed, the effect will be the creation of a new
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table with the specified list of column names (order matters!).
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A column name is always an atom.
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If a table with the given name already exists, the predicate must throw a
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descriptive exception (use throw/1).
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All exceptions must have a descriptive error message.
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If a table with the given name already exists, the predicate throws a
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descriptive exception (using throw/1).
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*/
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create_table(Table, Cols) :-
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(tabl(Table, _) -> throw("Table already exists"));
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@ -81,8 +64,8 @@ row(Table, Row) :-
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:- dynamic rows/1.
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/*
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Displays all rows in the given table, one per line (use writeln/1).
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If the given table does not exist, the predicate must throw a descriptive
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Displays all rows in the given table, one per line (using writeln/1).
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If the given table does not exist, the predicate throws a descriptive
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exception.
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*/
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rows(Table) :-
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@ -108,10 +91,10 @@ When this predicate is executed, the effect will be the addition of a given
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row in the given table. The given row is a list of values for each of the
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corresponding columns in the table (in the order in which the columns
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were supplied to create table/2).
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If the given table does not exist, the predicate must throw a descriptive
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If the given table does not exist, the predicate throws a descriptive
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exception.
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If the row does not have as many elements as the number of columns in
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the table, the predicate must throw a descriptive exception.
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the table, the predicate throws a descriptive exception.
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*/
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insert(Table, Row) :-
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(tabl(Table, Cols) ->
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@ -127,10 +110,7 @@ insert(Table, Row) :-
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/*
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When this predicate is executed, the effect will be the deletion of the given
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table.
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Do make sure that all of its rows are deleted as well, so that they don’t
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magically reappear again if you would recreate a table with the same name
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and signature later on.
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If the given table does not exist, the predicate must throw a descriptive
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If the given table does not exist, the predicate throws a descriptive
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exception.
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*/
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drop(Table) :-
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@ -144,7 +124,7 @@ drop(Table) :-
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When this predicate is executed, the effect will be the deletion of all rows
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in the given table. The table itself should still exist after, but with no
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more rows.
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If the given table does not exist, the predicate must throw a descriptive
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If the given table does not exist, the predicate throws a descriptive
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exception.
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*/
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delete(Table) :-
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@ -157,13 +137,12 @@ delete(Table) :-
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/*
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When this predicate is executed, the effect will be the deletion of all rows
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from the given table that match all of the given conditions. The table
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must still exist after.
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If the given table does not exist, the predicate must throw a descriptive
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still exist after.
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If the given table does not exist, the predicate throws a descriptive
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exception.
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A condition is any Prolog predicate that could have been typed at the
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prompt, but which may include selectors. Selectors are terms of the form
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+<column>where <column>should be replaced by a column name.
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(See tests.pl for some concrete usage examples.)
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*/
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delete(Table, Conds) :-
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(tabl(Table, _) ->
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@ -205,13 +184,11 @@ does_match([Cond|Rest], Table, Row) :-
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:- dynamic selec/4.
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/*
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Note that the name of this predicate is selec (without t) for the simple
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reason that select/4 is already a built-in Prolog predicate.
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Table is the name of a single table.
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Selectors is either * or a list of selectors. These define the resulting
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projection. * means: select all column names from the table. Other
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selectors explicitly specify which columns to pick. (See above for what
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selectors look like.) For example, +name would select the column named
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selectors explicitly specify which columns to pick.
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For example, +name would select the column named
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name.
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Conds has the same form as in delete/2 and works the same way: only
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rows that match all conditions are selected.
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@ -249,7 +226,10 @@ selec(Table, Selector, Cond, Projection) :-
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row(Table, R),
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does_match(Cond, Table, R),
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selector(R,Cols, Selector, [],[],ColumnNames,ColumnValue),
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Projection = ColumnNames/ColumnValue.
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reverse(ColumnNames, Names),
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reverse(ColumnValue, Values),
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Projection = Names/Values.
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selec(Table, *, Cond, Projection) :-
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tabl(Table, Cols),
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@ -264,7 +244,9 @@ selec(Table, *, Cond, Projection) :-
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* AccCols: acumulator list for the column(s) name(s)
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* AccVals: acumulator list for the row(s) values
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* ColumnNames: List returning the column(s) name(s)
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* ColumnValue: List returning the row values for each column
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* ColumnValue: List returning the row values for each column
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*
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* This predicate return
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*/
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selector(_,_,[],ColumnNames, ColumnValue, ColumnNames, ColumnValue):-!.
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@ -290,7 +272,10 @@ selec(TableOrTables, Selectors, Projection) :-
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tabl(TableOrTables, Cols),
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row(TableOrTables, R),
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selector(R,Cols, Selectors, [],[],ColumnNames,ColumnValue),
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Projection = ColumnNames/ColumnValue.
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reverse(ColumnNames, Names),
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reverse(ColumnValue, Values),
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Projection = Names/Values.
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selec(Table, *, Projection) :-
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tabl(Table, Cols),
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@ -396,7 +381,8 @@ parse_query(Query, insert, [AtomTable, Values]):-
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split_string(Query, " ", '",();', SplitQuery),
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append(["INSERT", "INTO"], L1, SplitQuery),
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L1 = [Table | L2],
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append(_, ["VALUES"|Values], L2),
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append(_, ["VALUES"|Values1], L2),
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maplist(is_number, Values, Values1),
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atom_string(AtomTable, Table).
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add_plus(+A, A).
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