ref: 7cea6be90dc64c7037bc25ccb5d3473e3bd261d7
dir: /ref.c/
#include <u.h>
#include <libc.h>
#include <ctype.h>
#include "git.h"
typedef struct Eval Eval;
typedef struct XObject XObject;
struct Eval {
char *str;
char *p;
Object **stk;
int nstk;
int stksz;
};
struct XObject {
Object *obj;
Object *mark;
XObject *queue;
XObject *next;
};
void
eatspace(Eval *ev)
{
while(isspace(ev->p[0]))
ev->p++;
}
int
objdatecmp(void *pa, void *pb)
{
Object *a, *b;
a = *(Object**)pa;
b = *(Object**)pb;
assert(a->type == GCommit && b->type == GCommit);
if(a->commit->mtime == b->commit->mtime)
return 0;
else if(a->commit->mtime < b->commit->mtime)
return -1;
else
return 1;
}
void
push(Eval *ev, Object *o)
{
if(ev->nstk == ev->stksz){
ev->stksz = 2*ev->stksz + 1;
ev->stk = erealloc(ev->stk, ev->stksz*sizeof(Object*));
}
ev->stk[ev->nstk++] = o;
}
Object*
pop(Eval *ev)
{
if(ev->nstk == 0)
sysfatal("stack underflow");
return ev->stk[--ev->nstk];
}
Object*
peek(Eval *ev)
{
if(ev->nstk == 0)
sysfatal("stack underflow");
return ev->stk[ev->nstk - 1];
}
int
isword(char e)
{
return isalnum(e) || e == '/' || e == '-' || e == '_' || e == '.';
}
int
word(Eval *ev, char *b, int nb)
{
char *p, *e;
int n;
p = ev->p;
for(e = p; isword(*e) && strncmp(e, "..", 2) != 0; e++)
/* nothing */;
/* 1 for nul terminator */
n = e - p + 1;
if(n >= nb)
n = nb;
snprint(b, n, "%s", p);
ev->p = e;
return n > 0;
}
int
take(Eval *ev, char *m)
{
int l;
l = strlen(m);
if(strncmp(ev->p, m, l) != 0)
return 0;
ev->p += l;
return 1;
}
XObject*
hnode(XObject *ht[], Object *o)
{
XObject *h;
int hh;
hh = o->hash.h[0] & 0xff;
for(h = ht[hh]; h; h = h->next)
if(hasheq(&o->hash, &h->obj->hash))
return h;
h = malloc(sizeof(*h));
h->obj = o;
h->mark = nil;
h->queue = nil;
h->next = ht[hh];
ht[hh] = h;
return h;
}
Object*
ancestor(Object *a, Object *b)
{
Object *o, *p, *r;
XObject *ht[256];
XObject *h, *q, *q1, *q2;
int i;
if(a == b)
return a;
if(a == nil || b == nil)
return nil;
r = nil;
memset(ht, 0, sizeof(ht));
q1 = nil;
h = hnode(ht, a);
h->mark = a;
h->queue = q1;
q1 = h;
h = hnode(ht, b);
h->mark = b;
h->queue = q1;
q1 = h;
while(1){
q2 = nil;
while(q = q1){
q1 = q->queue;
q->queue = nil;
o = q->obj;
for(i = 0; i < o->commit->nparent; i++){
p = readobject(o->commit->parent[i]);
h = hnode(ht, p);
if(h->mark != nil){
if(h->mark != q->mark){
r = h->obj;
goto done;
}
} else {
h->mark = q->mark;
h->queue = q2;
q2 = h;
}
}
}
if(q2 == nil){
werrstr("no common ancestor");
break;
}
q1 = q2;
}
done:
for(i=0; i<nelem(ht); i++){
while(h = ht[i]){
ht[i] = h->next;
free(h);
}
}
return r;
}
int
lca(Eval *ev)
{
Object *a, *b, *o;
if(ev->nstk < 2){
werrstr("ancestor needs 2 objects");
return -1;
}
a = pop(ev);
b = pop(ev);
o = ancestor(a, b);
if(o == nil)
return -1;
push(ev, o);
return 0;
}
int
parent(Eval *ev)
{
Object *o, *p;
o = pop(ev);
/* Special case: first commit has no parent. */
if(o->commit->nparent == 0 || (p = readobject(o->commit->parent[0])) == nil){
werrstr("no parent for %H", o->hash);
return -1;
}
push(ev, p);
return 0;
}
int
unwind(Eval *ev, Object **obj, int *idx, int nobj, Object **p, Objset *set, int keep)
{
int i;
for(i = nobj; i >= 0; i--){
idx[i]++;
if(keep && !oshas(set, obj[i])){
push(ev, obj[i]);
osadd(set, obj[i]);
}else{
osadd(set, obj[i]);
}
if(idx[i] < obj[i]->commit->nparent){
*p = obj[i];
return i;
}
}
return -1;
}
int
range(Eval *ev)
{
Object *a, *b, *p, **all;
int nall, *idx, mark;
Objset keep, skip;
b = pop(ev);
a = pop(ev);
if(a->type != GCommit || b->type != GCommit){
werrstr("non-commit object in range");
return -1;
}
p = b;
all = nil;
idx = nil;
nall = 0;
mark = ev->nstk;
osinit(&keep);
osinit(&skip);
while(1){
all = erealloc(all, (nall + 1)*sizeof(Object*));
idx = erealloc(idx, (nall + 1)*sizeof(int));
all[nall] = p;
idx[nall] = 0;
if(p == a)
if((nall = unwind(ev, all, idx, nall, &p, &keep, 1)) == -1)
break;
else if(p->commit->nparent == 0)
if((nall = unwind(ev, all, idx, nall, &p, &skip, 0)) == -1)
break;
else if(oshas(&keep, p))
if((nall = unwind(ev, all, idx, nall, &p, &keep, 1)) == -1)
break;
else if(oshas(&skip, p))
if((nall = unwind(ev, all, idx, nall, &p, &skip, 0)) == -1)
break;
if(p->commit->nparent == 0)
break;
if((p = readobject(p->commit->parent[idx[nall]])) == nil)
sysfatal("bad commit %H", p->commit->parent[idx[nall]]);
nall++;
}
free(all);
qsort(ev->stk + mark, ev->nstk - mark, sizeof(Object*), objdatecmp);
return 0;
}
int
readref(Hash *h, char *ref)
{
static char *try[] = {"", "refs/", "refs/heads/", "refs/remotes/", "refs/tags/", nil};
char buf[256], s[256], **pfx;
int r, f, n;
/* TODO: support hash prefixes */
if((r = hparse(h, ref)) != -1)
return r;
if(strcmp(ref, "HEAD") == 0){
snprint(buf, sizeof(buf), ".git/HEAD");
if((f = open(buf, OREAD)) == -1)
return -1;
if((n = readn(f, s, sizeof(s) - 1))== -1)
return -1;
s[n] = 0;
strip(s);
r = hparse(h, s);
goto found;
}
for(pfx = try; *pfx; pfx++){
snprint(buf, sizeof(buf), ".git/%s%s", *pfx, ref);
if((f = open(buf, OREAD)) == -1)
continue;
if((n = readn(f, s, sizeof(s) - 1)) == -1)
continue;
s[n] = 0;
strip(s);
r = hparse(h, s);
close(f);
goto found;
}
return -1;
found:
if(r == -1 && strstr(s, "ref: ") == s)
r = readref(h, s + strlen("ref: "));
return r;
}
int
evalpostfix(Eval *ev)
{
char name[256];
Object *o;
Hash h;
eatspace(ev);
if(!word(ev, name, sizeof(name))){
werrstr("expected name in expression");
return -1;
}
if(readref(&h, name) == -1){
werrstr("could not resolve ref %s", name);
return -1;
}else if((o = readobject(h)) == nil){
werrstr("invalid ref %s (hash %H)", name, h);
return -1;
}
push(ev, o);
while(1){
eatspace(ev);
switch(ev->p[0]){
case '^':
ev->p++;
if(parent(ev) == -1)
return -1;
break;
case '@':
ev->p++;
if(lca(ev) == -1)
return -1;
break;
default:
goto done;
break;
}
}
done:
return 0;
}
int
evalexpr(Eval *ev, char *ref)
{
memset(ev, 0, sizeof(*ev));
ev->str = ref;
ev->p = ref;
while(1){
if(evalpostfix(ev) == -1)
return -1;
if(ev->p[0] == '\0')
return 0;
else if(take(ev, ":") || take(ev, "..")){
if(evalpostfix(ev) == -1)
return -1;
if(ev->p[0] != '\0'){
werrstr("junk at end of expression");
return -1;
}
return range(ev);
}
}
}
int
resolverefs(Hash **r, char *ref)
{
Eval ev;
Hash *h;
int i;
if(evalexpr(&ev, ref) == -1){
free(ev.stk);
return -1;
}
h = emalloc(ev.nstk*sizeof(Hash));
for(i = 0; i < ev.nstk; i++)
h[i] = ev.stk[i]->hash;
*r = h;
return ev.nstk;
}
int
resolveref(Hash *r, char *ref)
{
Eval ev;
if(evalexpr(&ev, ref) == -1){
free(ev.stk);
return -1;
}
if(ev.nstk != 1){
werrstr("ambiguous ref expr");
free(ev.stk);
return -1;
}
*r = ev.stk[0]->hash;
return 0;
}