From 9d9100f05f1189314a4f0a5fdd70934a9de4c1ba Mon Sep 17 00:00:00 2001
From: An-Cheng Huang <ancheng@vyatta.com>
Date: Tue, 18 Jan 2011 15:24:21 -0800
Subject: add comments for context diff code
---
src/cnode/cnode-algorithm.cpp | 100 +++++++++++++++++++++++++++++++++++++++++-
1 file changed, 98 insertions(+), 2 deletions(-)
(limited to 'src/cnode')
diff --git a/src/cnode/cnode-algorithm.cpp b/src/cnode/cnode-algorithm.cpp
index 23b5b41..526a218 100644
--- a/src/cnode/cnode-algorithm.cpp
+++ b/src/cnode/cnode-algorithm.cpp
@@ -212,6 +212,9 @@ _diff_print_indent(const CfgNode *cfg1, const CfgNode *cfg2, int level,
}
}
+/* this is used by "context diff" to print the context in "edit notation"
+ * like in JUNOS "show | compare".
+ */
static void
_diff_print_context(vector<string>& cur_path)
{
@@ -222,6 +225,18 @@ _diff_print_context(vector<string>& cur_path)
printf("]\n");
}
+/* print the comment (if any) at the specified node, including "change
+ * prefix" (if any).
+ *
+ * since a node's comment is printed before the node itself, this will
+ * print the "context" first if doing context diff.
+ *
+ * cur_path: the current context (for context diff).
+ * context_diff: whether we're doing context diff.
+ *
+ * return whether anything is printed. this is only used for context diff
+ * (caller does different things according to return value).
+ */
static bool
_diff_print_comment(const CfgNode *cfg1, const CfgNode *cfg2, int level,
vector<string>& cur_path, bool context_diff)
@@ -260,9 +275,15 @@ _diff_print_comment(const CfgNode *cfg1, const CfgNode *cfg2, int level,
// no comment
return false;
}
+ /* print comment if
+ * * not doing context diff
+ * OR
+ * * doing context diff and there is actually a difference
+ */
if (!context_diff || (pfx_diff != PFX_DIFF_NONE.c_str()
&& pfx_diff != PFX_DIFF_NULL.c_str())) {
if (context_diff) {
+ // print context first
_diff_print_context(cur_path);
}
_diff_print_indent(cfg1, cfg2, level, pfx_diff);
@@ -299,6 +320,11 @@ _diff_check_and_show_leaf(const CfgNode *cfg1, const CfgNode *cfg2, int level,
bool cprint = _diff_print_comment(cfg1, cfg2, level, cur_path, context_diff);
if (cprint) {
+ /* when doing context diff, normally we only show the node if there is a
+ * difference. however, if something was printed for comment, the node
+ * should be printed even if there is no difference. so set context_diff
+ * to false to force the node to be displayed.
+ */
context_diff = false;
}
if (cfg->isMulti()) {
@@ -306,9 +332,13 @@ _diff_check_and_show_leaf(const CfgNode *cfg1, const CfgNode *cfg2, int level,
if (force_pfx_diff) {
// simple case: just use the same diff prefix for all values
if (!cprint && context_diff) {
+ /* if nothing was printed for comment and we're doing context diff,
+ * then context hasn't been displayed yet. so print it first.
+ */
_diff_print_context(cur_path);
}
if (!context_diff || force_pfx_diff != PFX_DIFF_NULL.c_str()) {
+ // not context diff OR there is a difference => print the node
const vector<string>& vvec = cfg->getValues();
for (size_t i = 0; i < vvec.size(); i++) {
_diff_print_indent(cfg1, cfg2, level, force_pfx_diff);
@@ -323,11 +353,19 @@ _diff_check_and_show_leaf(const CfgNode *cfg1, const CfgNode *cfg2, int level,
vector<const char *> pfxs;
bool changed = _cmp_multi_values(cfg1, cfg2, values, pfxs);
if (!context_diff || changed) {
+ // not context diff OR there is a difference => print the node
for (size_t i = 0; i < values.size(); i++) {
if (context_diff && pfxs[i] == PFX_DIFF_NONE.c_str()) {
+ // not printing unchanged values if doing context diff
continue;
}
if (!cprint && context_diff) {
+ /* if nothing was printed for comment and we're doing context
+ * diff, then context hasn't been displayed yet. so print it
+ * first. note that we only want to see the context once, so
+ * set cprint to true so that later iterations won't print it
+ * again.
+ */
_diff_print_context(cur_path);
cprint = true;
}
@@ -354,7 +392,11 @@ _diff_check_and_show_leaf(const CfgNode *cfg1, const CfgNode *cfg2, int level,
bool changed = (force_pfx_diff != PFX_DIFF_NONE.c_str()
&& force_pfx_diff != PFX_DIFF_NULL.c_str());
if (!context_diff || changed) {
+ // not context diff OR there is a difference => print the node
if (!cprint && context_diff) {
+ /* if nothing was printed for comment and we're doing context diff,
+ * then context hasn't been displayed yet. so print it first.
+ */
_diff_print_context(cur_path);
}
_diff_print_indent(cfg1, cfg2, level, force_pfx_diff);
@@ -401,10 +443,39 @@ _diff_show_other(const CfgNode *cfg1, const CfgNode *cfg2, int level,
if (print_this) {
bool cprint = _diff_print_comment(cfg1, cfg2, level, cur_path, orig_cdiff);
if (orig_cdiff && pfx_diff != PFX_DIFF_NONE.c_str()) {
+ /* note:
+ * orig_cdiff is the original value of context_diff.
+ * pfx_diff is set above.
+ * so the condition here means
+ * (1) when this function is called, we are doing a context diff
+ * AND
+ * (2) pfx_diff is either PFX_DIFF_ADD or PFX_DIFF_DEL, i.e., one
+ * and only one of cfg1 and cfg2 is NULL.
+ *
+ * note that pfx_diff cannot be PFX_DIFF_NULL since
+ * (cfg1 == cfg2) cannot be true if context_diff is true (see
+ * caller's logic).
+ *
+ * since one and only one of cfg1 and cfg2 is NULL, it means that the
+ * whole subtree rooted at the current node is "added" or "deleted".
+ * therefore, set context_diff to false for the recursion into this
+ * subtree so that it will be displayed normally.
+ */
context_diff = false;
}
if (cprint || !orig_cdiff || pfx_diff != PFX_DIFF_NONE.c_str()) {
+ /* print this node if
+ * (1) something was printed for comment, in which case the node
+ * should be printed regardless of whether there is a difference.
+ * OR
+ * (2) not doing context diff.
+ * OR
+ * (3) there is a difference.
+ */
if (!cprint && orig_cdiff) {
+ /* if nothing was printed for comment and we're doing context diff,
+ * then context hasn't been displayed yet. so print it first.
+ */
_diff_print_context(cur_path);
}
_diff_print_indent(cfg1, cfg2, level, pfx_diff);
@@ -415,7 +486,22 @@ _diff_show_other(const CfgNode *cfg1, const CfgNode *cfg2, int level,
// at intermediate node
printf("%s", name.c_str());
}
- if (cprint && pfx_diff == PFX_DIFF_NONE.c_str()) {
+ if (cprint && orig_cdiff && pfx_diff == PFX_DIFF_NONE.c_str()) {
+ /* the condition means:
+ * (1) something was printed for comment.
+ * AND
+ * (2) doing context diff.
+ * AND
+ * (3) there is no difference for the node itself.
+ *
+ * this means we are only printing the node for the comment. so just
+ * print "{ ... }" to represent the subtree like JUNOS
+ * "show | compare". any difference in the subtree will be handled
+ * later by the recursion into it.
+ *
+ * in this case also set is_leaf_typeless to true to prevent a
+ * dangling "}\n" from being printed at the end of this function.
+ */
printf(" { ... }\n");
is_leaf_typeless = true;
} else {
@@ -443,6 +529,10 @@ _diff_show_other(const CfgNode *cfg1, const CfgNode *cfg2, int level,
cur_path.pop_back();
}
if (!orig_cdiff || pfx_diff != PFX_DIFF_NONE.c_str()) {
+ /* not context diff OR there is a difference => print closing '}'
+ * if necessary. also note the exception above where is_leaf_typeless
+ * is set to true to prevent this.
+ */
if (!is_leaf_typeless) {
_diff_print_indent(cfg1, cfg2, level, pfx_diff);
printf("}\n");
@@ -484,9 +574,15 @@ _show_diff(const CfgNode *cfg1, const CfgNode *cfg2, int level,
if (context_diff) {
if (cfg1 == cfg2) {
- // nothing to do for context diff
+ /* nothing to do for context diff so stop the recursion. this also
+ * means that during the recursion cfg1 and cfg2 must be different
+ * if doing context diff.
+ */
return;
}
+ /* when doing context diff, the display indentation level always starts
+ * at 0.
+ */
level = 0;
}
--
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