54 lines
1.3 KiB
Java
54 lines
1.3 KiB
Java
package cobalt.lang;
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import java.util.HashMap;
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import java.util.Map;
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class Environment {
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final Environment enclosing;
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private final Map<String, Object> values = new HashMap<>();
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Environment() {
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enclosing = null;
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}
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Environment(Environment enclosing) {
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this.enclosing = enclosing;
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}
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Object get(Token name) {
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if (values.containsKey(name.lexeme)) {
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return values.get(name.lexeme);
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}
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if (enclosing != null) return enclosing.get(name);
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throw new RuntimeError(name,
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"Undefined reference to variable: '" + name.lexeme + "'.");
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}
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void define(Token name, Object value) {
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if (!values.containsKey(name.lexeme)) {
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values.put(name.lexeme, value);
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} else {
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throw new RuntimeError(name,
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"Undefined reference to variable: '" + name.lexeme + "'.");
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}
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}
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void assign(Token name, Object value) {
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if (values.containsKey(name.lexeme)) {
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values.put(name.lexeme, value);
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return;
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}
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if (enclosing != null) {
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enclosing.assign(name, value);
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return;
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}
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throw new RuntimeError(name,
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"Undefined variable '" + name.lexeme + "'.");
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}
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} |