https://github.com/jedwards1211/segment-java

keeps track of where text is located in a file during parsing and prints it underlined in context
https://github.com/jedwards1211/segment-java

parsing

Last synced: about 15 hours ago
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keeps track of where text is located in a file during parsing and prints it underlined in context

• Host: GitHub
• URL: https://github.com/jedwards1211/segment-java
• Owner: jedwards1211
• Created: 2016-10-19T23:49:49.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2019-02-28T05:02:34.000Z (almost 6 years ago)
• Last Synced: 2024-11-09T06:40:55.105Z (about 2 months ago)
• Topics: parsing
• Language: Java
• Size: 27.3 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# segment-java

Displaying good parse error messages was hard, until I created this!

## Usage

It's very simple: you wrap a `String` and add the source file, start line, and start column, like so:

```java

Segment segment = new Segment(text, "somefile.txt", startLine, startCol);

```

`Segment` implements `CharSequence` and has almost the exact same API as `String` so you can use it just like you would

use a `String` in parsing.  And here's why you want to: as you `split` it or make `substring`s, etc., it returns new `Segments` 

that know where they are located in the file:

```java

for (Segment line : segment.split("\r\n|\r|\n") {

    System.out.println(line.startLine);

}

```

prints:

```

0

1

2

...etc

```

It also provides an `underlineInContext` method that's useful for showing where syntax errors are located:

```java

Segment segment = new Segment("there is an error here", "somefile.txt", 0, 0);

System.out.println(segment.split("\\s+")[4].underlineInContext());

```

prints:

```

there is an error here

                  ^^^^

```

This package also provides `SegmentMatcher` since it would be impossible to call `Pattern.matcher(segment)`:

```java

SegmentMatcher matcher = new SegmentMatcher(new Segment("hello world"), "somefile.txt", 0, 0), Pattern.compile("world"));

matcher.find();

Segment match = matcher.group();

System.out.println(match.underlineInContext());

```

prints:

```

hello world

      ^^^^^

```