Add sam_hdr_passes_filter() for SAM header filter expressions

Makefile

@@ -359,7 +359,7 @@ hts-object-files: $(LIBHTS_OBJS)
 bgzf.o bgzf.pico: bgzf.c config.h $(htslib_hts_h) $(htslib_bgzf_h) $(htslib_hfile_h) $(htslib_thread_pool_h) $(htslib_hts_endian_h) cram/pooled_alloc.h $(hts_internal_h) $(htslib_khash_h)
 errmod.o errmod.pico: errmod.c config.h $(htslib_hts_h) $(htslib_ksort_h) $(htslib_hts_os_h)
 kstring.o kstring.pico: kstring.c config.h $(htslib_kstring_h)
-header.o header.pico: header.c config.h $(textutils_internal_h) $(header_h)
+header.o header.pico: header.c config.h $(htslib_hts_expr_h) $(textutils_internal_h) $(header_h)
 hfile.o hfile.pico: hfile.c config.h $(htslib_hfile_h) $(hfile_internal_h) $(htslib_kstring_h) $(hts_internal_h) $(htslib_khash_h)
 hfile_gcs.o hfile_gcs.pico: hfile_gcs.c config.h $(htslib_hts_h) $(htslib_kstring_h) $(hfile_internal_h)
 hfile_libcurl.o hfile_libcurl.pico: hfile_libcurl.c config.h $(hfile_internal_h) $(htslib_hts_h) $(htslib_kstring_h) $(htslib_khash_h)

header.c

@@ -34,6 +34,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <string.h>
 #include <assert.h>
 #include <errno.h>
+#include "htslib/hts_expr.h"
 #include "textutils_internal.h"
 #include "header.h"
 
@@ -898,6 +899,84 @@ static int sam_hrecs_parse_lines(sam_hrecs_t *hrecs, const char *hdr, size_t len
     return 0;
 }
 
+static int sam_hrecs_tag_lookup(sam_hrec_type_t *h_type, const char *tagname,
+                                char type, hts_expr_val_t *result) {
+    sam_hrec_tag_t *tag = sam_hrecs_find_key(h_type, tagname, NULL);
+    if (tag == NULL || tag->len < 3) {
+        result->is_str = (type == 'Z');
+        result->s.l = 0;
+        result->d = 0.0;
+        result->is_true = 0;
+        return 0;
+    }
+
+    result->is_true = 1;
+    switch (type) {
+    case 'f':
+        result->is_str = 0;
+        result->d = strtod(&tag->str[3], NULL);
+        return 0;
+
+    case 'i':
+        result->is_str = 0;
+        result->d = strtoll(&tag->str[3], NULL, 0);
+        return 0;
+
+    case 'Z':
+        result->is_str = 1;
+        ks_clear(&result->s);
+        return (kputsn(&tag->str[3], tag->len-3, &result->s) >= 0)? 0 : -1;
+    }
+
+    return -1;
+}
+
+static int sam_hrecs_sym_lookup(void *data, char *str, char **end,
+                                hts_expr_val_t *result) {
+    sam_hrec_type_t *h_type = (sam_hrec_type_t *) data;
+
+    switch (*str) {
+    case 't':
+        if (memcmp(str, "type", 4) == 0) {
+            *end = &str[4];
+            result->is_str = 1;
+            ks_clear(&result->s);
+            kputc_(h_type->type >> 8, &result->s);
+            kputc(h_type->type & 0xff, &result->s);
+            return (ks_len(&result->s) == 2)? 0 : -1;
+        }
+        break;
+
+    case '@':
+        if (isalpha_c(str[1]) && isalpha_c(str[2])) {
+            *end = &str[3];
+            result->is_str = 0;
+            result->is_true = result->d = (h_type->type == TYPEKEY(&str[1]));
+            return 0;
+        }
+        break;
+
+    case '[':
+        if (str[1] & str[2]) {
+            if (str[3] == ']') {
+                *end = &str[4];
+                return sam_hrecs_tag_lookup(h_type, &str[1], 'Z', result);
+            }
+            else if (str[3] == ':' && str[4] && str[5] == ']') {
+                if (!strchr("fiZ", str[4])) {
+                    hts_log_error("Unrecognised %.6s type code", str);
+                    return -1;
+                }
+                *end = &str[6];
+                return sam_hrecs_tag_lookup(h_type, &str[1], str[4], result);
+            }
+        }
+        break;
+    }
+
+    return -1;
+}
+
 /*! Update sam_hdr_t target_name and target_len arrays
  *
  *  @return 0 on success; -1 on failure
@@ -1762,6 +1841,21 @@ int sam_hdr_remove_lines(sam_hdr_t *bh, const char *type, const char *id, void *
     return ret;
 }
 
+int sam_hdr_passes_filter(sam_hdr_t *bh, sam_hdr_line_itr_t *iter, hts_filter_t *filt) {
+    hts_expr_val_t result;
+    int ret;
+    if (hts_filter_eval(filt, iter, sam_hrecs_sym_lookup, &result) >= 0) {
+        ret = result.is_true;
+    }
+    else {
+        hts_log_error("Couldn't process sam_hdr filter expression");
+        ret = -1;
+    }
+
+    hts_expr_val_free(&result);
+    return ret;
+}
+
 int sam_hdr_count_lines(sam_hdr_t *bh, const char *type) {
     int count;
     sam_hrec_type_t *first_ty, *itr_ty;

htslib/sam.h

@@ -37,6 +37,7 @@ DEALINGS IN THE SOFTWARE.  */
 extern "C" {
 #endif
 
+struct hts_filter_t;
 struct sam_hrec_type_s;
 
 /// Highest SAM format version supported by this library
@@ -845,6 +846,15 @@ hts_pos_t sam_hdr_tid2len(const sam_hdr_t *h, int tid);
  */
 static inline int bam_name2id(sam_hdr_t *h, const char *ref) { return sam_hdr_name2tid(h, ref); }
 
+/// Check whether a header line passes an hts_filter
+/** @param h      Pointer to the header structure previously read
+ *  @param iter   Iterator pointing to a header line
+ *  @param filt   Pointer to the filter, created from hts_filter_init
+ *  @return       1 if it passes, 0 if not, and <0 on error
+ */
+HTSLIB_EXPORT
+int sam_hdr_passes_filter(sam_hdr_t *h, sam_hdr_line_itr_t *iter, struct hts_filter_t *filt);
+
 /// Generate a unique \@PG ID: value
 /*!
  * @param name  Name of the program. Eg. samtools
@@ -1483,9 +1493,6 @@ const char *sam_parse_region(sam_hdr_t *h, const char *s, int *tid,
     HTSLIB_EXPORT
     int sam_write1(samFile *fp, const sam_hdr_t *h, const bam1_t *b) HTS_RESULT_USED;
 
-// Forward declaration, see hts_expr.h for full.
-struct hts_filter_t;
-
 /// sam_passes_filter - Checks whether a record passes an hts_filter.
 /** @param h      Pointer to the header structure previously read
  *  @param b      Pointer to the BAM record to be checked