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# (DD08) Business Logic — PatternAExtractor.extractVersion() [5 LOC]

| Field | Value |
|-------|-------|
| Fully Qualified Name | `com.optage.parser.PatternAExtractor` |
| Layer | Utility |
| Module | `parser` (Package: `com.optage.parser`) |

## 1. Role

### PatternAExtractor.extractVersion()

This method extracts a version token from a single source line by applying a fixed regular-expression rule and returning the first matching version-like substring. In business terms, it acts as a lightweight text parser for metadata lines, normalizing version information into a canonical value such as `v1.0` or `v2.3.4` when that token is present. If the input line does not contain a version expression, the method returns an empty string, which signals that the line is not a version-bearing record.

The method is a small routing-style utility rather than a domain service: it does not persist data, call external systems, or transform multiple entities. Its role in the larger system is to support a broader parsing workflow by isolating version detection logic into a reusable helper. The design pattern is straightforward pattern matching / extraction, using a compiled regular expression and a conditional branch to decide whether a match exists. There are only two outcomes: a successful version extraction path and a fallback empty-result path.

## 2. Processing Pattern (Detailed Business Logic)

```mermaid
flowchart TD
    START(["extractVersion(line)"])
    STEP1["Compile version regex pattern v[\\d.]+"]
    STEP2["Create matcher from input line"]
    DECISION{"matcher.find()?"}
    STEP3["Return matcher.group()"]
    STEP4["Return empty string"]
    END_NODE(["Return / Next"])

    START --> STEP1
    STEP1 --> STEP2
    STEP2 --> DECISION
    DECISION -->|Yes| STEP3
    DECISION -->|No| STEP4
    STEP3 --> END_NODE
    STEP4 --> END_NODE
```

## 3. Parameter Analysis

| No | Parameter Name | Type | Business Description |
|----|---------------|------|---------------------|
| 1 | `line` | `String` | A single text line from the source content that may contain a version marker. The method scans this line for the first substring matching the version pattern `v` followed by digits and dots. If a matching version token exists, that token is returned; otherwise, the method yields an empty string to indicate that no version information was found. |

Instance fields or external state read by the method: none. The method is self-contained and depends only on the supplied `line` value and locally created regex objects.

## 4. CRUD Operations / Called Services

This method does not perform CRUD operations against any database, entity, or external service. It only performs in-memory string parsing using `Pattern.compile`, `matcher`, `find`, and `group`.

| CRUD | SC / CBS | SC Code | Entity / DB | Operation Description |
|------|----------|---------|-------------|-----------------------|
| - | `Pattern.compile` | - | - | Compiles a regular expression used to detect a version token in a line of text. |
| - | `matcher` | - | - | Creates a regex matcher over the supplied line. |
| - | `find` | - | - | Searches the line for the first version-like substring. |
| - | `group` | - | - | Returns the matched version token when a match exists. |

## 5. Dependency Trace

### Pre-computed evidence from code analysis graph:

No screen/batch entry points found within 8 hops. Direct callers found: 1 method.
Terminal operations from this method: -

Trace who calls this method and what this method ultimately calls.

| # | Caller (Screen/Batch) | Call Chain (Full Path to this Method) | Terminal (SC / CRUD / Entity) |
|---|----------------------|--------------------------------------|--------------------------------|
| 1 | `PatternAExtractor` internal parser flow | `PatternAExtractor.parseLine` -> `PatternAExtractor.extractVersion` | `extractVersion [R] in-memory regex match` |

## 6. Per-Branch Detail Blocks

**Block 1** — **EXEC** `(method entry)` (L55)

> Initializes the version extraction workflow for a single source line.

| # | Type | Code |
|---|------|------|
| 1 | SET | `Pattern versionPattern = Pattern.compile("v[\\d.]+");` // build a version-matching regex |
| 2 | SET | `Matcher matcher = versionPattern.matcher(line);` // create a matcher for the input line |

**Block 2** — **IF** `(matcher.find())` (L58)

> Determines whether the current line contains a version token.

| # | Type | Code |
|---|------|------|
| 1 | EXEC | `matcher.find();` // search for the first matching version substring |
| 2 | RETURN | `return matcher.group();` // return the matched version token |

**Block 3** — **ELSE** `(no version token found)` (L58)

> Handles lines that do not contain a parseable version marker.

| # | Type | Code |
|---|------|------|
| 1 | RETURN | `return "";` // return empty string to signal no version information |

## 7. Glossary

| Term | Type | Business Meaning |
|------|------|------------------|
| `line` | Field | Input text line being parsed for metadata. |
| `version` | Business term | A release identifier expressed as a letter `v` followed by digits and dot separators, such as `v1.0` or `v2.3.4`. |
| regex | Technical term | Regular expression used to identify pattern-based text tokens. |
| matcher | Technical term | Regex evaluation object that scans the input text for a match. |
| `find` | Technical term | Regex operation that searches for the first matching substring. |
| `group` | Technical term | Regex operation that returns the matched substring. |
| parser | Module term | A utility package that extracts structured values from unstructured source text. |
| Utility | Layer | A helper component that performs local, stateless text processing. |
| `v[\\d.]+` | Pattern | Version-matching rule: the letter `v` followed by one or more digits or dots. |
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