refactor: build logic

.gitignore

@@ -4,3 +4,4 @@ results/
 .history
 *.so
 *.bc
+tags

Makefile

@@ -4,7 +4,7 @@ EXTVERSION = 0.1
 DATA = $(wildcard sql/*--*.sql)
 
 MODULE_big = $(EXTENSION)
-OBJS = src/plmustache.o src/observation.o
+OBJS = src/plmustache.o src/observation.o src/build.o
 
 TESTS = $(wildcard test/sql/*.sql)
 REGRESS = $(patsubst test/sql/%.sql,%,$(TESTS))

src/build.c

@@ -0,0 +1,167 @@
+#include <postgres.h>
+
+#include <tcop/utility.h>
+#include <utils/builtins.h>
+#include <utils/varlena.h>
+
+#include <utils/syscache.h>
+#include <utils/lsyscache.h>
+#include <funcapi.h>
+#include <catalog/pg_proc.h>
+#include <catalog/pg_type.h>
+#include <access/htup_details.h>
+
+#include <mustach/mustach.h>
+
+#include "observation.h"
+#include "build.h"
+
+const char IMPLICIT_ITERATOR = '.';
+
+static int
+plmustache_enter_section(void *userdata, const char *name){
+  plmustache_ctx *ctx = (plmustache_ctx *)userdata;
+
+  for(size_t i = 0; i < ctx->num_params; i++){
+    plmustache_param* prm = &ctx->params[i];
+
+    if(strcmp(prm->prm_name, name) == 0){
+      return prm->enters_section;
+    }
+  }
+
+  return 0;
+}
+
+// TODO these are used to handle sections, they're mandatory otherwise mustach segfaults
+static int plmustache_next(void *closure){
+  return MUSTACH_OK;
+}
+
+static int
+plmustache_leave(void *closure){
+  return MUSTACH_OK;
+}
+
+static int
+plmustache_get_variable(void *userdata, const char *name, struct mustach_sbuf *sbuf){
+  plmustache_ctx *ctx = (plmustache_ctx *)userdata;
+
+  for(size_t i = 0; i < ctx->num_params; i++){
+    plmustache_param* prm = &ctx->params[i];
+
+    if(strcmp(prm->prm_name, name) == 0){
+      sbuf->value = prm->prm_value;
+    }
+  }
+
+  return MUSTACH_OK;
+}
+
+struct mustach_itf build_mustach_itf(){
+  return (struct mustach_itf)
+  { .enter  = plmustache_enter_section
+  , .next   = plmustache_next
+  , .leave  = plmustache_leave
+  , .get    = plmustache_get_variable
+  };
+}
+
+static char *
+datum_to_cstring(Datum datum, Oid typeoid, plmustache_obs_handler observer)
+{
+  HeapTuple typetuple = SearchSysCache(TYPEOID, ObjectIdGetDatum(typeoid), 0, 0, 0);
+  if (!HeapTupleIsValid(typetuple))
+    observer((plmustache_observation){ERROR_NO_TYPE_OID, .error_type_oid = typeoid});
+
+  Form_pg_type pg_type_entry = (Form_pg_type) GETSTRUCT(typetuple);
+
+  Datum ret = OidFunctionCall1(pg_type_entry->typoutput, datum);
+
+  ReleaseSysCache(typetuple);
+
+  return DatumGetCString(ret);
+}
+
+
+plmustache_call_info
+build_call_info(Oid function_oid, FunctionCallInfo fcinfo, plmustache_obs_handler observer){
+  HeapTuple proc_tuple = SearchSysCache(PROCOID, ObjectIdGetDatum(function_oid), 0, 0, 0);
+  if (!HeapTupleIsValid(proc_tuple))
+    observer((plmustache_observation){ERROR_NO_OID, .error_function_oid = function_oid});
+
+  bool is_null;
+  Oid prorettype = SysCacheGetAttr(PROCOID, proc_tuple, Anum_pg_proc_prorettype, &is_null);
+  if(is_null)
+    observer((plmustache_observation){ERROR_NO_RETTYPE});
+
+  Datum prosrc = SysCacheGetAttr(PROCOID, proc_tuple, Anum_pg_proc_prosrc, &is_null);
+  if(is_null)
+    observer((plmustache_observation){ERROR_NO_SRC});
+
+  Oid* argtypes; char** argnames; char* argmodes;
+  int numargs = get_func_arg_info(proc_tuple, &argtypes, &argnames, &argmodes);
+
+  if(argmodes) // argmodes is non-NULL when any of the parameters are OUT or INOUT
+    observer((plmustache_observation){ERROR_NOT_ONLY_IN_PARAMS});
+
+  // This already prevents functions from being used as triggers.
+  // So it's not necessary to use CALLED_AS_TRIGGER and CALLED_AS_EVENT_TRIGGER
+  if(getBaseType(prorettype) != TEXTOID)
+    observer((plmustache_observation){ERROR_NO_TEXT_RET});
+
+  // when having a single unnamed parameter, the argnames are NULL
+  if (!argnames && numargs == 1)
+    observer((plmustache_observation){ERROR_UNNAMED_PARAMS});
+  for(size_t i = 0; i < numargs; i++){
+    if (strlen(argnames[i]) == 0)
+      observer((plmustache_observation){ERROR_UNNAMED_PARAMS});
+    if (argnames[i][0] == IMPLICIT_ITERATOR)
+      observer((plmustache_observation){ERROR_PARAM_IMPLICIT_ITERATOR, .error_implicit_iterator = IMPLICIT_ITERATOR});
+  }
+
+  return (plmustache_call_info)
+  { proc_tuple
+  , prosrc
+  , numargs
+  , argtypes
+  , argnames
+  };
+}
+
+plmustache_ctx
+build_mustache_ctx(plmustache_call_info call_info, NullableDatum args[]){
+  plmustache_ctx ctx = {0};
+
+  ctx.template = TextDatumGetCString(DirectFunctionCall2(btrim, call_info.prosrc, CStringGetTextDatum("\n")));
+
+  if(call_info.numargs > 0){
+    plmustache_param *params = palloc0(sizeof(plmustache_param) * call_info.numargs);
+    ctx.num_params = call_info.numargs;
+    ctx.params = params;
+
+    for(size_t i = 0; i < call_info.numargs; i++){
+      params[i].prm_name = call_info.argnames[i];
+      NullableDatum arg = args[i];
+      if(arg.isnull){
+        params[i].prm_value = NULL;
+        params[i].enters_section = false;
+      }else{
+        params[i].prm_value = datum_to_cstring(arg.value, call_info.argtypes[i], ereporter);
+        if(call_info.argtypes[i] == BOOLOID)
+          params[i].enters_section = DatumGetBool(arg.value);
+        else
+          params[i].enters_section = true;
+      }
+    }
+  }
+
+  return ctx;
+}
+
+plmustache_ctx free_plmustache_ctx(plmustache_ctx ctx){
+  if(ctx.params) pfree(ctx.params);
+  if(ctx.template) pfree(ctx.template);
+  ctx = (plmustache_ctx){0};
+  return ctx;
+}

src/build.h

@@ -0,0 +1,38 @@
+#ifndef BUILD_H
+#define BUILD_H
+
+#include <mustach/mustach.h>
+#include <postgres.h>
+#include "observation.h"
+
+typedef struct {
+  char *prm_name;
+  char *prm_value;
+  bool enters_section;
+} plmustache_param;
+
+typedef struct {
+  size_t num_params;
+  plmustache_param *params;
+  char *template;
+} plmustache_ctx;
+
+typedef struct {
+  HeapTuple proc_tuple;
+  Datum prosrc;
+  int numargs;
+  Oid* argtypes;
+  char** argnames;
+} plmustache_call_info;
+
+struct mustach_itf build_mustach_itf(void);
+
+plmustache_call_info
+build_call_info(Oid function_oid, FunctionCallInfo fcinfo, plmustache_obs_handler observer);
+
+plmustache_ctx
+build_mustache_ctx(plmustache_call_info call_info, NullableDatum args[]);
+
+plmustache_ctx free_plmustache_ctx(plmustache_ctx ctx);
+
+#endif