1 files changed, 124 insertions, 0 deletions
diff --git a/workhorse/internal/lsif_transformer/parser/code_hover.go b/workhorse/internal/lsif_transformer/parser/code_hover.go
new file mode 100644
index 00000000000..dbdaba643d1
--- /dev/null
+++ b/workhorse/internal/lsif_transformer/parser/code_hover.go
@@ -0,0 +1,124 @@
+package parser
+
+import (
+	"encoding/json"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/alecthomas/chroma"
+	"github.com/alecthomas/chroma/lexers"
+)
+
+const maxValueSize = 250
+
+type token struct {
+	Class string `json:"class,omitempty"`
+	Value string `json:"value"`
+}
+
+type codeHover struct {
+	TruncatedValue *truncatableString `json:"value,omitempty"`
+	Tokens         [][]token          `json:"tokens,omitempty"`
+	Language       string             `json:"language,omitempty"`
+	Truncated      bool               `json:"truncated,omitempty"`
+}
+
+type truncatableString struct {
+	Value     string
+	Truncated bool
+}
+
+func (ts *truncatableString) UnmarshalText(b []byte) error {
+	s := 0
+	for i := 0; s < len(b); i++ {
+		if i >= maxValueSize {
+			ts.Truncated = true
+			break
+		}
+
+		_, size := utf8.DecodeRune(b[s:])
+
+		s += size
+	}
+
+	ts.Value = string(b[0:s])
+
+	return nil
+}
+
+func (ts *truncatableString) MarshalJSON() ([]byte, error) {
+	return json.Marshal(ts.Value)
+}
+
+func newCodeHover(content json.RawMessage) (*codeHover, error) {
+	// Hover value can be either an object: { "value": "func main()", "language": "go" }
+	// Or a string with documentation
+	// We try to unmarshal the content into a string and if we fail, we unmarshal it into an object
+	var c codeHover
+	if err := json.Unmarshal(content, &c.TruncatedValue); err != nil {
+		if err := json.Unmarshal(content, &c); err != nil {
+			return nil, err
+		}
+
+		c.setTokens()
+	}
+
+	c.Truncated = c.TruncatedValue.Truncated
+
+	if len(c.Tokens) > 0 {
+		c.TruncatedValue = nil // remove value for hovers which have tokens
+	}
+
+	return &c, nil
+}
+
+func (c *codeHover) setTokens() {
+	lexer := lexers.Get(c.Language)
+	if lexer == nil {
+		return
+	}
+
+	iterator, err := lexer.Tokenise(nil, c.TruncatedValue.Value)
+	if err != nil {
+		return
+	}
+
+	var tokenLines [][]token
+	for _, tokenLine := range chroma.SplitTokensIntoLines(iterator.Tokens()) {
+		var tokens []token
+		var rawToken string
+		for _, t := range tokenLine {
+			class := c.classFor(t.Type)
+
+			// accumulate consequent raw values in a single string to store them as
+			// [{ Class: "kd", Value: "func" }, { Value: " main() {" }] instead of
+			// [{ Class: "kd", Value: "func" }, { Value: " " }, { Value: "main" }, { Value: "(" }...]
+			if class == "" {
+				rawToken = rawToken + t.Value
+			} else {
+				if rawToken != "" {
+					tokens = append(tokens, token{Value: rawToken})
+					rawToken = ""
+				}
+
+				tokens = append(tokens, token{Class: class, Value: t.Value})
+			}
+		}
+
+		if rawToken != "" {
+			tokens = append(tokens, token{Value: rawToken})
+		}
+
+		tokenLines = append(tokenLines, tokens)
+	}
+
+	c.Tokens = tokenLines
+}
+
+func (c *codeHover) classFor(tokenType chroma.TokenType) string {
+	if strings.HasPrefix(tokenType.String(), "Keyword") || tokenType == chroma.String || tokenType == chroma.Comment {
+		return chroma.StandardTypes[tokenType]
+	}
+
+	return ""
+}