C++: QLDoc.

Author: geoffw0

cpp/ql/src/semmle/code/cpp/models/implementations/Pure.qll

@@ -3,7 +3,10 @@ import semmle.code.cpp.models.interfaces.Taint
 import semmle.code.cpp.models.interfaces.Alias
 import semmle.code.cpp.models.interfaces.SideEffect
 
-/** Pure string functions. */
+/**
+ * A function that operates on strings and is pure. That is, its evaluation is
+ * guaranteed to be side effect-free.
+ */
 private class PureStrFunction extends AliasFunction, ArrayFunction, TaintFunction,
   SideEffectFunction {
   PureStrFunction() {
@@ -89,7 +92,9 @@ private string strcmp() {
     ]
 }
 
-/** String standard `strlen` function, and related functions for computing string lengths. */
+/**
+ * A function such as `strlen` that returns the length of the given string.
+ */
 private class StrLenFunction extends AliasFunction, ArrayFunction, SideEffectFunction {
   StrLenFunction() {
     hasGlobalOrStdOrBslName(["strlen", "strnlen", "wcslen"])
@@ -123,7 +128,10 @@ private class StrLenFunction extends AliasFunction, ArrayFunction, SideEffectFun
   }
 }
 
-/** Pure functions. */
+/**
+ * A function that is pure, that is, its evaluation is guaranteed to be side
+ * effect-free. Excludes functions modeled by `PureStrFunction` and `PureMemFunction`.
+ */
 private class PureFunction extends TaintFunction, SideEffectFunction {
   PureFunction() { hasGlobalOrStdOrBslName(["abs", "labs"]) }
 
@@ -140,7 +148,10 @@ private class PureFunction extends TaintFunction, SideEffectFunction {
   override predicate hasOnlySpecificWriteSideEffects() { any() }
 }
 
-/** Pure raw-memory functions. */
+/**
+ * A function that operates on memory buffers and is pure. That is, its
+ * evaluation is guaranteed to be side effect-free.
+ */
 private class PureMemFunction extends AliasFunction, ArrayFunction, TaintFunction,
   SideEffectFunction {
   PureMemFunction() {