---
title: Parse version input
summary: Split a caller-supplied version string into the library's four stored segments.
status: draft
owner: SAIF Team
last_reviewed: 2026-07-30
library: SAIF.Framework.Version
reference_type: package
operation_id: OP-VER-001
trigger: Caller constructs New Version(input) or invokes Version.Parse(input)
---

# Parse version input

This operation turns a dot-delimited string such as `"1.2.3.4"` into a fully populated `Version` instance. It backs two entry points: the shared `Version.Parse(input)` factory method, and the `New Version(input)` string constructor, which calls `Parse` internally and copies the result onto the instance being constructed.

| Field | Value |
| --- | --- |
| **Operation ID** | `OP-VER-001` |
| **Trigger** | Caller constructs `New Version(input)` or invokes `Version.Parse(input)` |
| **Inputs** | `input As String` |
| **Outputs** | New `Version` instance with `Major`, `Minor`, `Build`, and `Revision` populated |
| **Primary components** | `Version.New(input As String)`, `Version.Parse(input As String)` |
| **Entry point** | `SAIF.Framework.Version\Version.vb` |

## Steps

1. If the caller used the string constructor, `New Version(input)` delegates immediately to `Version.Parse(input)` and applies the returned segments to the new instance.
2. Split `input` on the `.` character to produce `versionParts`.
   - On failure: if `input` is `Nothing`, `String.Split` throws, and because there is no local guard, the exception propagates unchanged to the caller.
3. Seed local working variables with the defaults `major = "1"`, `minor = "0"`, `build = "0"`, and `revision = "0"`.
4. Overwrite `major` with `versionParts(0)`.
   - If the first token is blank: the blank value replaces the `"1"` default, so a leading empty segment is never defaulted — only the trailing segments benefit from the seeded defaults.
5. Copy `versionParts(1)`, `versionParts(2)`, and `versionParts(3)` into `minor`, `build`, and `revision` respectively, but only for indexes that the split actually produced; any index the input omits keeps its seeded `"0"` value ([BR-002](../business-rules.md#br-002-missing-trailing-version-segments-default-to-0-when-parsing)).
   - If `input` contains more than four dot-separated segments: every token beyond index `3` is ignored and never surfaces in the result.
6. Construct `New Version(major, minor, build, revision)` and return it to the caller.
   - If this path was entered from the string constructor: the constructor's internal `Update` step copies these four segment values onto the instance under construction, so the caller sees a fully initialized object rather than the intermediate result.

## Process flow

The following diagram visualizes this operation's control flow.

```mermaid
flowchart TD
	Start([Caller provides version string]) --> Split[Split input on dot]
	Split --> Defaults[Seed local segment defaults]
	Defaults --> Major[Overwrite Major with first segment]
	Major --> Missing{Trailing segments present?}
	Missing -->|Yes| Copy[Copy available trailing segments]
	Missing -->|No| Keep[Keep seeded 0 defaults]
	Copy --> BuildVersion[Construct new Version instance]
	Keep --> BuildVersion
	BuildVersion --> EndOk([Return populated Version instance])
```

## Failure and edge-case behavior

- A `Nothing` `input` is not caught locally; the runtime exception from `String.Split` surfaces directly to the caller.
- The `major = "1"` seed only matters when the split itself fails to produce a first token, which does not happen for any non-null input; in practice, `Major` is always taken verbatim from the first dot-separated segment, blank or not.
- Segments beyond the fourth are silently dropped — a five-part input such as `"1.2.3.4.5"` parses identically to `"1.2.3.4"`.

## Related documentation
- [Operations and processes](../operations-processes.md)
- [Business rules](../business-rules.md)

## Sources
- `SAIF.Framework.Version\Version.vb`