proc: simplify next/step/stepout condition code

Adds a library of utility functions to generated breakpoint conditions
for next, step and stepout.

pkg/astutil/astutil.go

@@ -0,0 +1,40 @@
+// This package contains utility functions used by pkg/proc to generate
+// ast.Expr expressions.
+
+package astutil
+
+import (
+	"go/ast"
+	"go/token"
+	"strconv"
+)
+
+// Eql returns an expression evaluating 'x == y'.
+func Eql(x, y ast.Expr) *ast.BinaryExpr {
+	return &ast.BinaryExpr{Op: token.EQL, X: x, Y: y}
+}
+
+// Sel returns an expression evaluating 'x.sel'.
+func Sel(x ast.Expr, sel string) *ast.SelectorExpr {
+	return &ast.SelectorExpr{X: x, Sel: &ast.Ident{Name: sel}}
+}
+
+// PkgVar returns an expression evaluating 'pkg.v'.
+func PkgVar(pkg, v string) *ast.SelectorExpr {
+	return &ast.SelectorExpr{X: &ast.Ident{Name: pkg}, Sel: &ast.Ident{Name: v}}
+}
+
+// Int returns an expression representing the integer 'n'.
+func Int(n int64) *ast.BasicLit {
+	return &ast.BasicLit{Kind: token.INT, Value: strconv.FormatInt(n, 10)}
+}
+
+// And returns an expression evaluating 'x && y'.
+func And(x, y ast.Expr) *ast.BinaryExpr {
+	return &ast.BinaryExpr{Op: token.LAND, X: x, Y: y}
+}
+
+// Or returns an expression evaluating 'x || y'.
+func Or(x, y ast.Expr) *ast.BinaryExpr {
+	return &ast.BinaryExpr{Op: token.LOR, X: x, Y: y}
+}