Upstream itchyny/gojq state of the touched files before 6352bdeffe

inplace.go

@@ -1,46 +1,30 @@
 package gojq
 
-// This file implements the static analysis deciding whether the accumulated
+// Static analysis deciding whether the accumulated value of a reduce
-// value of a reduce expression may be updated in place; see
+// expression may be updated in place; see compiler#compileReduce. The checks
-// compiler#compileReduce for how the result is used, and the comment on
+// are conservative: failing them only keeps the previous copying behavior.
-// compiler#compileAssign for why an allocator makes assignments cheap.
-//
-// Reusing an allocator across the iterations of a reduce expression is only
-// correct while the accumulated value, and the values the allocator created
-// inside it, are reachable through the accumulated value alone. The checks
-// below are deliberately conservative; failing them only means the assignment
-// keeps copying the accumulated value, which is the previous behavior.
 
 // inPlaceUpdate reports whether the query is a single assignment applied to
-// the input value, and returns its operands. Such an assignment receives the
+// the input value, and returns its operands.
-// accumulated value of the enclosing reduce expression, and passes it on as
-// the next accumulated value, without any other part of the query observing
-// it in between.
 func (e *Query) inPlaceUpdate() (l, r *Query, op Operator, ok bool) {
 	if e.Term != nil || len(e.FuncDefs) > 0 {
 		return nil, nil, 0, false
 	}
 	switch e.Op {
 	case OpModify:
-		// The update function is applied to the values found at the target
+		// _modify releases the allocator before calling the update function.
-		// paths, so it never observes the input value itself. When a target
-		// path points to a value the allocator created, _modify releases the
-		// allocator before calling the update function.
 		return e.Left, e.Right, e.Op, true
 	case OpAssign:
-		// An assignment to a constant path is compiled to a setpath call,
+		// A constant path compiles to setpath, which uses no allocator.
-		// which does not use an allocator; see compiler#compileQueryUpdate.
 		if e.Left.toIndices(nil) != nil {
 			return nil, nil, 0, false
 		}
 		fallthrough
 	case OpUpdateAdd, OpUpdateSub, OpUpdateMul,
 		OpUpdateDiv, OpUpdateMod, OpUpdateAlt:
-		// The right-hand side is evaluated against the input value, so it must
+		// The right-hand side must neither observe the input value, which it
-		// not observe it; the assigned value would otherwise be able to alias
+		// could otherwise alias, nor yield multiple values, which would run
-		// the value it is assigned into. It must not yield multiple values
+		// the assignment against an already modified input.
-		// either, because the assignment then runs once per value, each time
-		// against an input value the previous run already modified.
 		if !e.Right.readsInput() && e.Right.singleValued() {
 			return e.Left, e.Right, e.Op, true
 		}
@@ -59,9 +43,7 @@ func (e *Query) readsInput() bool {
 	}
 	switch e.Op {
 	case OpPipe:
-		// The right-hand side is evaluated against the output of the
+		// Binding variables also exposes the input to the right-hand side.
-		// left-hand side, unless the query binds variables, in which case it
-		// is evaluated against the input value as well.
 		if len(e.Patterns) > 0 {
 			return e.Left.readsInput() || e.Right.readsInput()
 		}
@@ -118,8 +100,7 @@ func (e *Term) readsInput() bool {
 	case TermTypeUnary:
 		return e.Unary.Term.readsInput()
 	case TermTypeFunc:
-		// Only a variable reference is known not to read the input value; any
+		// Any function may be redefined, so only $x is known not to read it.
-		// function may be redefined, so its name tells us nothing.
 		return e.Func.Name[0] != '$' || len(e.Func.Args) > 0
 	case TermTypeQuery:
 		return e.Query.readsInput()
@@ -160,8 +141,7 @@ func (e *Term) singleValued() bool {
 }
 
 func (e *Suffix) readsInput() bool {
-	// Both iterating and the optional operator work on the value of the term,
+	// Only an index is evaluated against the input value.
-	// while an index is evaluated against the input value.
 	return e.Index != nil && e.Index.readsInput()
 }
 
@@ -205,8 +185,7 @@ func (e *String) singleValued() bool {
 
 func (e *ObjectKeyVal) readsInput() bool {
 	if e.Val == nil {
-		// The shorthand {foo} and {"foo"} read the input value, while {$foo}
+		// {foo} reads the input value, {$foo} does not.
-		// does not.
 		return e.Key == "" || e.Key[0] != '$'
 	}
 	if e.KeyString != nil && e.KeyString.readsInput() ||