Added basic linting of parsed JSON

README.md

@@ -1,4 +1,4 @@
 # gojson
 
-JSON Parser built with the help of ChatGPT 4.0.
+JSON Parser built with the help of ChatGPT 4.0.
-Grammar used is https://fullstack.wiki/syntax/rfc8259/index.
+Grammar used is https://fullstack.wiki/syntax/rfc8259/index.

linter/linter.go

@@ -0,0 +1,94 @@
+// Package linter provides functionality for linting JSON strings.
+package linter
+
+import (
+	"fmt"
+	"strings"
+
+	"gitea.paas.celticinfo.fr/oabrivard/gojson/lexer"
+	"gitea.paas.celticinfo.fr/oabrivard/gojson/parser"
+)
+
+// JsonLinter struct holds references to a lexer and a parser for JSON linting.
+type JsonLinter struct {
+	lexer  *lexer.Lexer   // The lexer to tokenize the input
+	parser *parser.Parser // The parser to parse the tokenized input
+}
+
+// NewJsonLinter creates and initializes a new JsonLinter with the given input string.
+func NewJsonLinter(input string) *JsonLinter {
+	l := lexer.NewLexer(input)
+	p := parser.NewParser(l)
+	return &JsonLinter{lexer: l, parser: p}
+}
+
+// Lint performs the linting process on the input JSON.
+// It parses the input and then formats it into a nicely structured JSON string.
+func (jl *JsonLinter) Lint() (string, error) {
+	parsedObject := jl.parser.Parse()
+
+	// If parsing errors are present, return an aggregated error message.
+	if len(jl.parser.Errors()) > 0 {
+		return "", fmt.Errorf("parsing errors: %v", jl.parser.Errors())
+	}
+
+	// Use the custom formatJSON function to format the parsed JSON object.
+	formattedJson := formatJSON(parsedObject, "")
+	return string(formattedJson), nil
+}
+
+// formatJSON formats any JSON value into a nicely indented string.
+func formatJSON(obj interface{}, indent string) string {
+	// Type switch to handle different types of JSON values.
+	switch v := obj.(type) {
+	case parser.JsonObject:
+		return formatObject(v, indent) // Format a JSON object
+	case parser.JsonArray:
+		return formatArray(v, indent) // Format a JSON array
+	case string:
+		return fmt.Sprintf("\"%s\"", v) // Format a JSON string
+	case nil:
+		return "null" // Format a JSON null
+	case bool:
+		if v {
+			return "true"
+		}
+		return "false"
+	default: // For numbers and other types, use default formatting
+		return fmt.Sprintf("%v", v)
+	}
+}
+
+// formatObject formats a JSON object into a string with proper indentation.
+func formatObject(obj map[string]interface{}, indent string) string {
+	var result strings.Builder
+	result.WriteString("{\n")
+	i := 0
+	for k, v := range obj {
+		// Format each key-value pair in the object.
+		result.WriteString(indent + "  \"" + k + "\": " + formatJSON(v, indent+"  "))
+		if i < len(obj)-1 {
+			result.WriteString(",")
+		}
+		result.WriteString("\n")
+		i++
+	}
+	result.WriteString(indent + "}")
+	return result.String()
+}
+
+// formatArray formats a JSON array into a string with proper indentation.
+func formatArray(array []interface{}, indent string) string {
+	var result strings.Builder
+	result.WriteString("[\n")
+	for i, v := range array {
+		// Format each value in the array.
+		result.WriteString(indent + "  " + formatJSON(v, indent+"  "))
+		if i < len(array)-1 {
+			result.WriteString(",")
+		}
+		result.WriteString("\n")
+	}
+	result.WriteString(indent + "]")
+	return result.String()
+}

linter/linter_test.go

@@ -0,0 +1,64 @@
+package linter
+
+import (
+	"testing"
+)
+
+func TestLintSimpleObject(t *testing.T) {
+	input := `{"name": "John", "age": 30, "isStudent": false}`
+
+	jl := NewJsonLinter(input)
+	linted, err := jl.Lint()
+
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+
+	expected := "{\n  \"name\": \"John\",\n  \"age\": 30,\n  \"isStudent\": false\n}"
+
+	if linted != expected {
+		t.Errorf("linted object is not as expected. Got %+v, want %+v", linted, expected)
+	}
+}
+
+func TestLintComplexObject(t *testing.T) {
+	input := `{
+		"key": "value",
+		"key-n": 101,
+		"key-o": {
+			"inner key": "inner value"
+		},
+		"key-l": ["list value"]
+	}`
+
+	jl := NewJsonLinter(input)
+	linted, err := jl.Lint()
+
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+
+	expected := "{\n  \"key\": \"value\",\n  \"key-n\": 101,\n  \"key-o\": {\n    \"inner key\": \"inner value\"\n  },\n  \"key-l\": [\n    \"list value\"\n  ]\n}"
+
+	if linted != expected {
+		t.Errorf("linted object is not as expected. Got %+v, want %+v", linted, expected)
+	}
+}
+
+func TestLintInvalidJson(t *testing.T) {
+	input := `{
+		"key": "value",
+		"key-n": 101,
+		"key-o": {
+			"inner key": "inner value"
+		},
+		"key-l": ['list value']
+	}`
+
+	jl := NewJsonLinter(input)
+	_, err := jl.Lint()
+
+	if err == nil {
+		t.Errorf("Expected error(s) during linting")
+	}
+}

parser/parser.go

@@ -220,6 +220,10 @@ func (p *Parser) expectPeek(t token.TokenType) bool {
 	}
 }
 
+func (p *Parser) Errors() []string {
+	return p.errors
+}
+
 // curTokenIs checks if the current token is of a specific type.
 func (p *Parser) curTokenIs(t token.TokenType) bool {
 	return p.curToken.Type == t