Initial commit

.github/workflows/lint_test.yml

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+name: lint and test
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+
+      - name: Check out
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: 'go.mod'
+
+      - name: Lint
+        uses: golangci/golangci-lint-action@v6
+        with:
+          # Require: The version of golangci-lint to use.
+          version: latest
+
+      - name: Test
+        run: go test -v

.golangci.yml

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+linters:
+  enable:
+    - revive
+    - gofumpt
+    - errorlint
+    - godot
+    - errname

LICENSE

@@ -0,0 +1,22 @@
+MIT License
+
+Copyright (c) 2024 Marcel Meyer [email protected]
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# Annot
+
+Annotate a string line with arrows leading to a description.
+
+```
+The quick brown fox jumps over the lazy dog
+      ↑     ↑                       ↑
+      │     └─ adjective            └─ adjective
+      │
+      └─ adjective
+```
+
+## Installation
+
+```
+go get github.com/meyermarcel/annot
+```
+
+## Example
+
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/meyermarcel/annot"
+)
+
+func main() {
+	fmt.Println("The quick brown fox jumps over the lazy dog")
+	fmt.Println(annot.String(
+		&annot.Annot{Col: 6, Lines: []string{"adjective"}},
+		&annot.Annot{Col: 12, Lines: []string{"adjective"}},
+		&annot.Annot{Col: 36, Lines: []string{"adjective"}},
+	))
+}
+```
+
+Output:
+
+```
+The quick brown fox jumps over the lazy dog
+      ↑     ↑                       ↑
+      │     └─ adjective            └─ adjective
+      │
+      └─ adjective
+```

annot.go

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+package annot
+
+import (
+	"fmt"
+	"io"
+	"slices"
+	"strings"
+	"unicode/utf8"
+)
+
+type Annot struct {
+	Col   int
+	Lines []string
+
+	row               int
+	lines             []*line
+	pipeLeadingSpaces []int
+}
+
+type line struct {
+	length        int
+	leadingSpaces int
+}
+
+type section int
+
+// #   |                 column |0123456789...
+// ----+------------------------+-------------------------------------------------
+// row | section                |     ↓ column position of annotation
+// -   | not relevant           |     ↑
+// 0· ·| above · · · · · · · · ·|· ·██│· · · · · · · · · · · · · · · · · · · · · ·
+// 1   | above                  |   ██│
+// 2· ·| linesFirstTwo · · · · ·|· ·██└─ line1 · · · · row position of annotation
+// 3   | linesFirstTwo          |   █████line2
+// 4· ·| linesAfterSecond· · · ·|· · · ██line3 · · · · · · · · · · · · · · · · · ·
+// 5   | linesAfterSecond       |      ██line4
+// 6· ·| trailingSpaceLines(1) ·|· · · ███████ · · · · · · · · · · · · · · · · · ·
+// 7   | noAnnot                |
+// 8· ·| noAnnot · · · · · · · ·|· · · · · · · · · · · · · · · · · · · · · · · · ·
+// 9   | noAnnot                |
+// ----+------------------------+-------------------------------------------------
+// #   |                        |   █ = needed space.
+const (
+	above section = iota
+	linesFirstTwo
+	linesAfterSecond
+	trailingSpaceLines
+	noAnnot
+)
+
+func (a *Annot) AddLines(lines ...string) {
+	a.Lines = append(a.Lines, lines...)
+}
+
+func String(annots ...*Annot) string {
+	b := &strings.Builder{}
+	_ = Write(b, annots...)
+	return b.String()
+}
+
+func Write(w io.Writer, annots ...*Annot) error {
+	annots = slices.CompactFunc(annots, func(a1 *Annot, a2 *Annot) bool {
+		return a1.Col == a2.Col
+	})
+
+	if len(annots) == 0 {
+		return nil
+	}
+
+	slices.SortFunc(annots, func(a *Annot, b *Annot) int {
+		return a.Col - b.Col
+	})
+
+	for _, a := range annots {
+		if len(a.Lines) == 0 {
+			a.lines = append(a.lines, &line{})
+			break
+		}
+		a.lines = make([]*line, len(a.Lines))
+		for i := range a.Lines {
+			a.lines[i] = &line{
+				//             3 for "└─ " or "   " (indentation)
+				length:        3 + utf8.RuneCountInString(a.Lines[i]),
+				leadingSpaces: a.Col,
+			}
+		}
+		a.pipeLeadingSpaces = make([]int, 0)
+	}
+
+	// Start with second last annotation index and decrement.
+	// The last annotation will always be on row=0 and needs
+	// no adjustment.
+	for aIdxDecr := len(annots) - 2; 0 <= aIdxDecr; aIdxDecr-- {
+		setRow(annots[aIdxDecr], annots[aIdxDecr+1:])
+	}
+
+	return write(w, annots)
+}
+
+func setRow(a *Annot, rightAnnots []*Annot) {
+	row := 0
+
+	for {
+		rowBefore := row - 1
+		if rowBefore != -1 {
+			setSpace(rowBefore, a, rightAnnots)
+		}
+
+		annotFits := checkLinesAndSetSpaces(row, a, rightAnnots)
+		if annotFits {
+			return
+		}
+		row++
+	}
+}
+
+func setSpace(rowBefore int, a *Annot, rightAnnots []*Annot) {
+	rightA, s := closestAnnot(rowBefore, rightAnnots, 0)
+	switch s {
+	case above:
+		rightA.pipeLeadingSpaces[rowBefore] = rightA.Col - a.Col - 1
+	case linesFirstTwo, linesAfterSecond:
+		rightA.lines[rowBefore-rightA.row].leadingSpaces = rightA.Col - a.Col - 1
+	case noAnnot, trailingSpaceLines:
+		// Do nothing
+	}
+}
+
+func checkLinesAndSetSpaces(row int, a *Annot, rightAnnots []*Annot) bool {
+	for aLineIdx := 0; aLineIdx < len(a.lines); aLineIdx++ {
+		lineFits := checkLineAndSetSpace(row, aLineIdx, a, rightAnnots)
+		if !lineFits {
+			return false
+		}
+	}
+	return true
+}
+
+func checkLineAndSetSpace(row, aLineIdx int, a *Annot, rightAnnots []*Annot) bool {
+	rowPlusLineIdx := row + aLineIdx
+
+	closestA, s := closestAnnot(rowPlusLineIdx, rightAnnots, 1)
+	if s == noAnnot {
+		return true
+	}
+
+	lineLength := a.lines[aLineIdx].length
+
+	remainingSpaces := closestA.Col - a.Col - lineLength
+
+	//                  |     ↑
+	// above            |   ██│
+	// above            |   ██│
+	// linesFirstTwo    |   ██└─ line1
+	// linesFirstTwo    |   ██   line2
+	// linesAfterSecond |        line3
+	//
+	// █ = needed space
+	if s == above || s == linesFirstTwo {
+		remainingSpaces -= 2
+	}
+
+	if remainingSpaces < 0 {
+		a.row++
+		a.pipeLeadingSpaces = append(a.pipeLeadingSpaces, a.Col)
+		return false
+	}
+
+	switch s {
+	case above:
+		closestA.pipeLeadingSpaces[rowPlusLineIdx] = remainingSpaces + 2
+	case linesFirstTwo:
+		closestA.lines[rowPlusLineIdx-closestA.row].leadingSpaces = remainingSpaces + 2
+	case linesAfterSecond:
+		closestA.lines[rowPlusLineIdx-closestA.row].leadingSpaces = remainingSpaces
+	case trailingSpaceLines:
+		closestA2, s2 := closestAnnot(rowPlusLineIdx, rightAnnots, 0)
+		if s2 == noAnnot {
+			return true
+		}
+		if s2 == above {
+			closestA2.pipeLeadingSpaces[rowPlusLineIdx] = closestA2.Col - a.Col - lineLength
+			break
+		}
+		closestA2.lines[rowPlusLineIdx-closestA2.row].leadingSpaces = closestA2.Col - a.Col - lineLength
+	default:
+		panic("should never be reached")
+	}
+	return true
+}
+
+func closestAnnot(row int, rightAnnots []*Annot, trailingVerticalSpaceLinesCount int) (*Annot, section) {
+	for _, a := range rightAnnots {
+		if row < a.row {
+			return a, above
+		}
+		if a.row <= row && row < a.row+len(a.lines) && row < 2 {
+			return a, linesFirstTwo
+		}
+		if 2 <= row && row < a.row+len(a.lines) {
+			return a, linesAfterSecond
+		}
+		if a.row+len(a.lines) <= row && row < a.row+len(a.lines)+trailingVerticalSpaceLinesCount {
+			return a, trailingSpaceLines
+		}
+
+	}
+	return nil, noAnnot
+}
+
+func write(writer io.Writer, annots []*Annot) error {
+	lastColPos := 0
+	rowCount := 0
+
+	b := &strings.Builder{}
+
+	for _, a := range annots {
+		b.WriteString(strings.Repeat(" ", a.Col-lastColPos))
+		b.WriteString("↑")
+		lastColPos = a.Col + 1
+
+		// Also use this loop to calculate rowCount
+		rowCount = max(rowCount, a.row+len(a.lines))
+	}
+	b.WriteString("\n")
+	_, err := fmt.Fprint(writer, b.String())
+	if err != nil {
+		return err
+	}
+	b.Reset()
+
+	for row := 0; row < rowCount; row++ {
+		for _, a := range annots {
+			switch {
+			case row < a.row:
+				b.WriteString(strings.Repeat(" ", a.pipeLeadingSpaces[row]))
+				b.WriteString("│")
+			case row == a.row:
+				b.WriteString(strings.Repeat(" ", a.lines[row-a.row].leadingSpaces))
+				b.WriteString("└─ ")
+				if len(a.Lines) != 0 {
+					b.WriteString(a.Lines[0])
+				}
+			case row < a.row+len(a.lines):
+				b.WriteString(strings.Repeat(" ", a.lines[row-a.row].leadingSpaces))
+				b.WriteString("   ")
+				b.WriteString(a.Lines[row-a.row])
+			}
+		}
+		b.WriteString("\n")
+		_, err = fmt.Fprint(writer, b.String())
+		if err != nil {
+			return err
+		}
+		b.Reset()
+	}
+
+	return nil
+}