Add ability to run statements without the macro

This is required to run highly dynamic SQL statements where the number of
parameters and the structure of results is only known dynamically.

Also fix typo s/SqliteDateType/SqliteDataType/

Author: mildred

src/easy_sqlite3.nim

@@ -1,4 +1,8 @@
 import easy_sqlite3/[bindings,macros]
 export macros
 
-export raw, len, toOpenArray, SQLiteError, SQLiteBlob, Statement, Database, OpenFlag, enableSharedCache, initDatabase, exec, execM, changes, lastInsertRowid, `[]=`, reset, step, withColumnBlob, getParameterIndex, getColumnType, getColumn, unpack, `=destroy`
+export raw, len, toOpenArray, SQLiteError, SQLiteBlob, Statement, Database,
+       SqliteDataType, OpenFlag, enableSharedCache, initDatabase, exec, execM,
+       changes, lastInsertRowid, `[]=`, reset, step, withColumnBlob,
+       getParameterIndex, getColumnType, getColumn, ColumnDef, columns, `[]`,
+       unpack, `=destroy`, newStatement, rows

src/easy_sqlite3/bindings.nim

@@ -224,7 +224,7 @@ type SqliteDestroctor* = proc (p: pointer) {.cdecl.}
 const StaticDestructor* = cast[SqliteDestroctor](0)
 const TransientDestructor* = cast[SqliteDestroctor](-1)
 
-type SqliteDateType* = enum
+type SqliteDataType* = enum
   dt_integer = 1,
   dt_float   = 2,
   dt_text    = 3,
@@ -385,7 +385,9 @@ proc sqlite3_bind_pointer*(st: ptr RawStatement, idx: int, val: pointer, name: c
 proc sqlite3_bind_zeroblob64*(st: ptr RawStatement, idx: int, len: int): ResultCode {.sqlite3linkage.}
 proc sqlite3_changes*(st: ptr RawDatabase): int {.sqlite3linkage.}
 proc sqlite3_last_insert_rowid*(st: ptr RawDatabase): int {.sqlite3linkage.}
-proc sqlite3_column_type*(st: ptr RawStatement, idx: int): SqliteDateType {.sqlite3linkage.}
+proc sqlite3_column_count*(st: ptr RawStatement): int {.sqlite3linkage.}
+proc sqlite3_column_type*(st: ptr RawStatement, idx: int): SqliteDataType {.sqlite3linkage.}
+proc sqlite3_column_name*(st: ptr RawStatement, idx: int): cstring {.sqlite3linkage.}
 proc sqlite3_column_blob*(st: ptr RawStatement, idx: int): pointer {.sqlite3linkage.}
 proc sqlite3_column_bytes*(st: ptr RawStatement, idx: int): int {.sqlite3linkage.}
 proc sqlite3_column_double*(st: ptr RawStatement, idx: int): float64 {.sqlite3linkage.}
@@ -497,6 +499,9 @@ proc `[]=`*[T](st: ref Statement, idx: int, val: Option[T]) =
   else:
     st[idx] = val.get
 
+proc `[]=`*[T](st: ref Statement, name: string, value: T) =
+  st[st.getParameterIndex(name)] = value
+
 proc reset*(st: ref Statement) =
   st.raw.sqliteCheck sqlite3_reset(st.raw)
 
@@ -515,7 +520,7 @@ proc withColumnBlob*(st: ref Statement, idx: int, recv: proc(vm: openarray[byte]
   let l = sqlite3_column_bytes(st.raw, idx)
   recv(cast[ptr UncheckedArray[byte]](p).toOpenArray(0, l))
 
-proc getColumnType*(st: ref Statement, idx: int): SqliteDateType =
+proc getColumnType*(st: ref Statement, idx: int): SqliteDataType =
   sqlite3_column_type(st.raw, idx)
 
 proc getColumn*(st: ref Statement, idx: int, T: typedesc[seq[byte]]): seq[byte] =
@@ -542,6 +547,31 @@ proc getColumn*[T](st: ref Statement, idx: int, _: typedesc[Option[T]]): Option[
   else:
     some(st.getColumn(idx, T))
 
+type ColumnDef* = object
+  st*:        ref Statement
+  idx*:       int
+  data_type*: SqliteDataType
+  name*:      string
+
+proc columns*(st: ref Statement): seq[ref ColumnDef] =
+  result = @[]
+  var idx = 0
+  let count = sqlite3_column_count(st.raw)
+  while idx < count:
+    let col = new(ColumnDef)
+    col.st = st
+    col.idx = idx
+    col.data_type = sqlite3_column_type(st.raw, idx)
+    col.name = $sqlite3_column_name(st.raw, idx)
+    result.add(col)
+    idx += 1
+
+proc `[]`*(st: ref Statement, idx: int): ref ColumnDef =
+  result = st.columns[idx]
+
+proc `[]`*[T](col: ref ColumnDef, t: typedesc[T]): T =
+  result = col.st.getColumn(col.idx, t)
+
 proc unpack*[T: tuple](st: ref Statement, _: typedesc[T]): T =
   var idx = 0
   for value in result.fields:
@@ -568,3 +598,10 @@ proc execM*(db: var Database, sqls: varargs[string]) {.discardable.} =
   except CatchableError:
     discard db.exec "ROLLBACK"
     raise getCurrentException()
+
+iterator rows*(st: ref Statement): seq[ref ColumnDef] =
+  try:
+    while st.step():
+      yield st.columns()
+  finally:
+    st.reset()