478. yāvat = [in order] that.

c.) When construed with the 1st person of the present, yāvat may also denote the purpose. In this case, the main sentence which generally precedes, is only expressive of some preparatory action to be completed „about the time” at which the action purposed is intended to take place; tāvat is as a rule omitted. Çâk. I sūta āśramoparodho sā bhūt tad ihaiva rathaṃ sthāpaya yāvad avatarāmi (charioteer, in order to avoid disturbing the hermitage, you must stop here, that I may descend), Kathâs. 16, 38 paramānnaṃ paceḥ śīghraṃ snātvā yāvad upaimy aham (cook an excellent meal for me, quickly, [that I may take it] when I come here after bathing), Vikram. V, p. 162 king to charioteer tadupaśleṣaya śaraṃ yāvan nirūpayāmi.

Rem. In this passage yāvat is construed with the 3d person of the imperative. Mhbh. 3, 72, 4 nigṛhīṣva… hayānetān… / vārṣṇeyo yāvad enaṃ me paṭamānayatām iha.

478. 「そのために」を表すyāvat

c.) Pres.1st.と文法的に結びつく場合、yāvatは目的をも表す。この場合、ふつう先行する主文は、意図される行為の〔これから〕行われることが〔動作主によって〕目論まれているその時点で（about the time）、既に完了されているべきである何らかの準備的行為を表現しているに過ぎない；tāvatは原則として省略される。
Çâk. I sūta āśramoparodho mā bhūt tad ihaiva rathaṃ sthāpaya yāvad avatarāmi (charioteer, in order to avoid disturbing the hermitage, you must stop here, that I may descend)
Kathâs. 16, 38 paramānnaṃ paceḥ śīghraṃ snātvā yāvad upaimy aham (cook an excellent meal for me, quickly, [that I may take it] when I come here after bathing)
Vikram. V, p. 162 king to charioteer tadupaśleṣaya śaraṃ yāvan nirūpayāmi

【補足】
以下の文では、yāvatはImpv.3rd.と文法的に結びついている。
Mhbh. 3, 72, 4 nigṛhīṣva… hayānetān… / vārṣṇeyo yāvad enaṃ me paṭamānayatām iha