Skip to content

Commit

Permalink
Add examples of @indexfor, @IndexOrHigh, @IndexOrLow.
Browse files Browse the repository at this point in the history
  • Loading branch information
mernst committed Jan 21, 2017
1 parent 5596a01 commit 3c2f654
Show file tree
Hide file tree
Showing 4 changed files with 72 additions and 7 deletions.
Expand Up @@ -7,6 +7,15 @@
* than both {@code a.length} and {@code b.length}. The sequences {@code a} and {@code b} might have
* different lengths.
*
* <p>The <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#charAt-int-">
* <code>String.charAt(int)</code></a> method is declared as
*
* <pre>{@code
* class String {
* char charAt(@IndexFor("this") index) { ... }
* }
* }</pre>
*
* <p>Writing {@code @IndexFor("arr")} is equivalent to writing {@link NonNegative @NonNegative}
* {@link LTLengthOf @LTLengthOf("arr")}, and that is how it is treated internally by the checker.
* Thus, if you write an {@code @IndexFor("arr")} annotation, you might see warnings about
Expand Down
Expand Up @@ -4,6 +4,16 @@
* An integer that, for each of the given sequences, is either a valid index or is equal to the
* sequence's length.
*
* <p>The <a
* href="https://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#binarySearch-java.lang.Object:A-int-int-java.lang.Object-">
* <code>Arrays.binarySearch</code></a> method is declared as
*
* <pre>{@code
* class Arrays {
* int binarySearch(Object[] a, @IndexFor("#1") int fromIndex, @IndexOrHigh("#1") int toIndex, Object key)
* }
* }</pre>
*
* <p>Writing {@code @IndexOrHigh("arr")} is equivalent to writing {@link NonNegative @NonNegative}
* {@link LTEqLengthOf @LTEqLengthOf("arr")}, and that is how it is treated internally by the
* checker. Thus, if you write an {@code @IndexFor("arr")} annotation, you might see warnings about
Expand Down
Expand Up @@ -3,6 +3,16 @@
/**
* An integer that is either -1 or is a valid index for each of the given sequences.
*
* <p>The <a
* href="https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#indexOf-java.lang.String-">
* <code>String.indexOf(String)</code></a> method is declared as
*
* <pre><code>
* class String {
* {@literal @}IndexOrLow("this") int indexOf(String str) { ... }
* }
* </code></pre>
*
* <p>Writing {@code @IndexOrLow("arr")} is equivalent to writing {@link
* GTENegativeOne @GTENegativeOne} {@link LTLengthOf @LTLengthOf("arr")}, and that is how it is
* treated internally by the checker. Thus, if you write an {@code @IndexOrLow("arr")} annotation,
Expand Down
50 changes: 43 additions & 7 deletions docs/manual/index-checker.tex
@@ -1,9 +1,12 @@
%\htmlhr
\chapter{Index Checker for sequence bounds (arrays, strings, lists)\label{index-checker}}
% Reinstate when lists are supported:
% \chapter{Index Checker for sequence bounds (arrays, strings, lists)\label{index-checker}}
\chapter{Index Checker for sequence bounds (arrays and strings)\label{index-checker}}

The Index Checker warns about potentially out-of-bounds accesses to sequence
data structures, such as arrays, lists, and strings.
(Note: Support for lists is not yet implemented.)
data structures, such as arrays
% , lists,
and strings.

The Index Checker prevents \<IndexOutOfBoundsException>s that result from
an index expression that might be negative or might be equal to or larger
Expand Down Expand Up @@ -60,7 +63,17 @@ \section{Index Checker structure and annotations\label{index-annotations}}

\begin{description}
\item[\refqualclasswithparams{checker/index/qual}{IndexFor}{String[] names}]
The value is a valid index for the named arrays. For example, a variable
The value is a valid index for the named arrays. For example, the
\sunjavadoc{java/lang/String.html\#charAt-int-}{String.charAt(int)}
method is declared as

\begin{Verbatim}
class String {
char charAt(@IndexFor("this") index) { ... }
}
\end{Verbatim}

More generally, a variable
declared as \<@IndexFor("someArray") int i> has type
\<@IndexFor("someArray") int> and its run-time value is guaranteed to be
non-negative and less than the length of \<someArray>. You could also
Expand All @@ -76,11 +89,34 @@ \section{Index Checker structure and annotations\label{index-annotations}}
\refqualclass{checker/index/qual}{NonNegative} and
\refqualclass{checker/index/qual}{LTEqLengthOf}.

For example, the
\sunjavadoc{java/util/Arrays.html\#binarySearch-java.lang.Object:A-int-int-java.lang.Object-}{Arrays.binarySearch}
method is declared as

\begin{mysmall}
\begin{Verbatim}
class Arrays {
int binarySearch(Object[] a, @IndexFor("#1") int fromIndex, @IndexOrHigh("#1") int toIndex, Object key)
}
\end{Verbatim}
\end{mysmall}

\item[\refqualclasswithparams{checker/index/qual}{IndexOrLow}{String[] names}]
The value is -1 or is a valid index for
each named array. This type combines
\refqualclass{checker/index/qual}{GTENegativeOne} and
\refqualclass{checker/index/qual}{LTEqLengthOf}.

For example, the
\sunjavadoc{java/lang/String.html\#indexOf-java.lang.String-}{String.indexOf(String)}
method is declared as

\begin{Verbatim}
class String {
@IndexOrLow("this") int indexOf(String str) { ... }
}
\end{Verbatim}

\end{description}

\section{Lower bounds\label{index-lowerbound}}
Expand Down Expand Up @@ -130,8 +166,8 @@ \section{Upper bounds\label{index-upperbound}}
qualifiers:

It issues an error when a sequence \code{arr}
is indexed by an integer that is not of type \code{@LTLengthOf({''arr''})}
or \code{@LTOMLengthOf({''arr''})}.
is indexed by an integer that is not of type \code{@LTLengthOf({"arr"})}
or \code{@LTOMLengthOf({"arr"})}.

\begin{description}

Expand Down Expand Up @@ -272,7 +308,7 @@ \section{Arrays of the same length\label{index-samelen}}
\item[\refqualclasswithparams{checker/index/qual}{SameLen}{String[] names}]
An expression with this type represents a sequence that has the
same length as the other sequences named in \<names>. In general,
\code{@SameLen} types that have non-intersecting lists of names
\code{@SameLen} types that have non-intersecting sets of names
are \textit{not} subtypes of each other. However, if at least one
sequence is named by both types, the types are actually the same,
because all the named sequences must have the same length.
Expand Down

0 comments on commit 3c2f654

Please sign in to comment.